Ignore the My Cloud stuff for the time being. If you’ve successfully indexed your music via the Sonos app, then from the Sonos app you should be able to use the browse option - the top option is Music Library. If you choose this then you should see a list of the ways that you can look at your music - e.g Artists, Albums etc. These use the tags in your music files, so will on’y be as accurate as the info in your files. I always use the Folders option at the bottom, as it shows be my (well organised, IMHO) folders on the disc. The folder view will show you the share that Sonos is using and clicking on that shows your folders. It’s a way of checking that the indexing has worked properly.

You add your NAS as a music library

 In the Sonos App

 click on settings, then system

 then scroll down to “Music library”

 then “Music library set up”

Then “Add shared music folder” and find the folder on your NAS where you’ve stored your music

I’m currently using the Music Library to access music from NAS. Simple. Don’t know why I didn’t look at that before. I assumed I needed the My Cloud Home app in order to stream music from NAS to Sonos. So what is the My Cloud Home app used for? Do I need it? Obviously it shows no music in there. So now that most of my music folder/files are in my WD NAS and on my Sonos app I don’t need to keep almost 1TB of music on my Windows laptop or old MAC anymore? I can delete them to open up more space on my drives? I have my NAS for storage/streaming and for backing up those files. I’ll also have my portable external hard drives for my music files as an extra protection? So can I access my Sonos and NAS from around the world to play music while I’m not home? 
What can you tell me about Plex? Or Twonky? That’s my next project. Lol. 1 step at a time. I have both apps in my WD My Cloud. I heard nice things about Plex. Do I need it? 
Thank you again Amun, BellyM, Ken Griffiths and bockersjv for your help. Much appreciated. It just took some patience and investigating to get it up and running. 

You don’t need Mycloud. Plex is a big worm hole. I’d get used to NAS drive favourites first. 
one thing I’d recommend is MP3Tag software. Helps sort all your tags and great for adding album art. 
Your NAS is your NAS, Sonos is just using it. If you want to access it adding the world then there are solutions to do so. These include cloud services. 
 

Personally i looked into all these. I ended up buying a dedicated music player that takes SD cards and regularly copy the NAS music directory to the SD card. Even 200gb cards are quite cheap.
 

I use Odroid HC Units which are similar to Raspberry Pi units.  Cheap and fun to configure and learn. 

Dcgman#1,

The SONOS library can include up to 65,000 tracks, however, if your Metadata (Album name, Track Title, Composer, etc.) is lengthy, you may run out of index space before reaching 65,000 tracks. Space is an issue because the index is stored in the SONOS players and they have finite RAM available. The SONOS library supports up to 16 segments. There is no need to delete any music files from the NAS. One solution for track overflow is to partition your library into multiple folders. For example you could have ‘music/Christmas’, ‘music/Halloween’, etc. and include only the folders appropriate for the season. Note that you have no control over the index build order. If the indexer terminates early, due to reaching a limit, and you try again, the list of tracks included will probably not be identical.

I don’t know how you built your library. While using the SONOS App to play music through the SONOS system, it is possible that nothing or very little will be listed in the Artist, Track, Composer, etc. sections of the library if there is no Metadata present in the track files, however, you will be able to see all of the tracks in the Folders section of the library.

If you have not already done this, disable the recycle bin of your NAS. Since you have no control over the library build order and the indexer will not process duplicates, you may encounter situations where changes to the Metadata will be ignored if the recycle folder is scanned first.

Okay so I’m back with another issue/question. I don’t think I’m connected to my NAS. Inside settings tab under Music Library Settings I’m showing the NAS with //MyCloudpr2100/music. But I also have 2 other music folders. One I used for my MAC and the other is my iTunes Media. So 3 total. My Sonos app isn’t recognizing the MyCloud folder. I power down both my MAC and laptop so my Sonos app should be able to see mycloud folder. When I click on a song in My Library it shows it cannot play because it can’t find the MAC or iTunes shared folder. How do I get my Sonos app to use the MyCloud folder? Do I need to remove the other 2 folders? For now I’m still using my MAC. And of course I’m using my new laptop. Both have the Sonos app installed. And both only recognize the Mac folder. Nothing see’s the MyCloud shared folder. Is it because I have too many files/songs? 65,000+ in my NAS.

i should also add after the initial music file transfer to the NAS I transferred more music and hit the Update Music Library Now. It was indexing but none of the new music transfer showed up in my files. 

In your SONOS controller define only the MyCloud folders, remove the MAC and laptop folders. In my scheme of seasonal music libraries your folder setup might become:

//MyCloudpr2100/music/core

//MyCloudpr2100/music/Christmas

//MyCloudpr2100/music/Halloween

Remember, you don’t have precise control over the order of library indexing and duplicate tracks will be ignored. For example, if the MAC track is encountered first, the MyCloud version of the track will become an ignored duplicate. Therefore, when the MAC is offline, the track will become ‘missing’.

There is no system harm with having 65,000+ tracks, but the human will be confused because the list of tracks falling in the ignored ‘+’ category might vary from run to run of the indexer. For example, if album ‘A’ has 20 tracks and on a given indexer run track #20 would become 65,001, the library will only list 19 tracks, but the next indexer run might include all 20 tracks from album ‘A’, but a track will be missing from album ‘B’. This results in confusion for the human, not a major problem for the system. If you are running into a Metadata space issue, the number of tracks included may vary from run to run. For example Classical Metadata is often more verbose than Pop Metadata. If the Classical tracks are processed first the limit might be reached at (for example) 42,000 tracks, but if the Pop music is indexed first, the limit might (for example) be 48,000 tracks. Again, there are no issues with respect to system stability, but the human might go ballistic.

BTW. SONOS never writes to (or deletes from) your music library.

This is my current Music Library:

//DavidguaniMac/itunes media

//DavidguaniMac/Music

//Mycloudpr2100/Music

After I turned off my Mac and laptop I tried to access My Library in Sonos and would get the error message:

Unable to play “song title” Unable to connect to //DavidguaniMac/Music, (but never see’s my //MyCloudpr2100/Music shared folder). 

if I delete the first 2 shared folders that would make the MyCloud folder the one and only folder that Sonos would see? Then my music should play on Sonos via MyCloud NAS? I’m a little slow in getting this as I’m trying to understand how NAS works with Sonos. I then need to make sub-folders of my music folder? 
//MyCloudpr2100/Music/Rock

//MyCloudpr2100/Music/Ambient

//MyCloudpr2100/Music/Jazz

Etc. Etc.

Yup. I figured this one out. I have to go in on my laptop to add or delete or moves files around.

SONOS supports up to 16 folders in the library. The subfolder structure is arbitrary, but the track limit is always 65,000.

For me one of the best aspects of SONOS is that I don’t need any music stored on my computer and the computer is not involved in playing music. When I’m developing software I’ll sometimes need to reboot my computer or if I’m rebuilding the computer, the music doesn’t stop. And, I’m a speed demon. Playing music saps some of the computer’s resources and slows things a bit. There is none of this with SONOS. Unless you are playing music stored on a computer or playing through an App, once you start a Playlist or online source, all of the computers and controllers can be shut down.

Since I’m a speed demon, if I’m on a major ripping project, I’ll rip to the computer and edit the Metadata on the computer files because this is much faster than dealing with a NAS across the network. After I’m satisfied with the Metadata, I’ll transfer the new arrivals to the NAS library. The transfer can be done in the background while I’m making a sandwich or I’m out and about.

Looking through my Sonos app I noticed my SonosNet was not connected. All my WM’s were 1, not 0. Found out my Boost plug was not plugged in. Must of unplugged a week or 2 ago while my son was moving items around in the room where the router and Boost are in. Anyways it’s back up and running. That has nothing to do with my Sonos not seeing the NAS. I also found that the the last music files did update in the WD NAS. It’s in My Cloud folders/files. But not in my iMac shared music files. I didn’t load them into it. Only into MyCloud shared music. I haven’t deleted the iMac or iTunes shared music yet as I have to go to a birthday party in a few. So I will continue this later today. Fingers crossed the Sonos will play off the MyCloud shared music after I delete the other 2. 

This is what I’m trying to accomplish. No music stored on my Computers. I want to play Sonos on the NAS. And have all my music and photos in NAS. Free up space and speed on my computers. 

Got home around 330. Took a nap. Must of been the IPA’s. Deleted the 2 music files. Redid the \\mycloud. Only one Sonos see’s now. Bingo. Got it! Thx again everyone. Mac is powered off. Laptop powered off. Next, cancel iCloud.