You can’t play your music folder from google drive.  You can, however, sign up for a free Google Play Music account, and upload your music library to that.  It works great, and syncs all iTunes playlists. works great on Sonos!

OK, thanks!

How to activate this in the app?

You will need to set up your Google Play Music account and download Google Music Manager  on a pc and upload your files first.  It takes quite a while for the upload to complete.  
 

After that, add Google Play Music as a music service In the Sonos app.  After you sign in to the service, you will have full access to your music library.  

Ok, thanks. 

I use the Sonos Android app and Google Play Music is only free for 30 days in Denmark, where I live.

Are there other possibilities?

@wltseng That would make Denmark an exception to the rule that you can upload 50.000 songs to Google Play Music and use those for free. This rule applies in the U.S. and the Netherlands at least. Are you sure you are right on this?

In order to initiate the free cloud storage, you do need to provide a credit card number and accept a 30 day free trial of their paid music streaming service.  Then, just cancel your free trial of the music streaming service. The free cloud storage of your personal library will still be available. 
 

At least that is how it works in U.S. 

Now it is working, thanks to 106rallye and wds0001.
I use Google Play Music for Chrome on my Windows 10 PC to transfer my music.

I have found that if I just open the Google Music app I can cast the podcasts, music stations, etc directly to the Sonos Play 1 speakers that I just bought. I can’t play them using the Sonos app but this method works beautifully, so both downloaded and streaming can be listened to.

Also just use the Music library on my PC through the Sonos App. No need to transfer music to get it there.

Thank you, just got sonos and have successfully followed your instructions, mucky buckets as we say over here!