If your router supports it, you can attach the SSD drive to the router’s USB port and use it as an NAS.  Then follow the instructions here:

https://support.sonos.com/s/article/78?language=en_US

Thanks Ken. When i connect the drive to my router, and a select add. It’s asking me for a path? Not sure where to find it. I see a IP address on the drive when i go into router settings 

You described it as an external USB SSD (Drive) - it’s not usual for such USB drives to have an IP address - what is it attached to?

My router. Maybe im mistaken regarding the IP address? Should i connect it to my IMac ?

Ah I now see it’s attached to your router, in that case see the link in jgatie’s post.

If you go into your router configuration pages and look at the USB share settings there, it will likely show you the ‘shared’ netbios name and/or IP address (same as router) and path/sharename and any password etc. 

You will likely have to go into the router configuration pages to enable the USB share anyway to begin with. 

If you have a router user-manual, that will likely explain what you first need to do to enable the USB share and it will likely show you the precise path to the shared library too, and perhaps provide a default username and password ? - although some routers may not always require a username/credentials etc; it depends on the router.

Once you establish the path (& any credentials) then add that to the area of the Sonos App as per your earlier posted screenshot.

Thanks. In my router settings, I don’t see a enable USB Share?

Can you perhaps provide a link to your routers user-manual online and I’ll see if I can discover anything further to assist you.

Thank you. Will look online for the users manual 

What make/model is it?

Verizon/Fios Home Router G3100

The initial link I came across was this:

https://internet-access-guide.com/verizon-fios-router-usb-external-hard-drive/

But I will do some more digging.

@Ken_Griffiths Thank you. Doesn’t look good. BTW i have Orbi mesh system. Maybe i can hook it usb to one of the satellites ?

And this link says the only thing the G3100 USB port can be used for is a 5v power supply:

https://www.joshualowcock.com/reviews/review-new-verizon-g3100-wifi-6-mesh-router/

So it looks like your out of luck using that router to share your SSD/Library across the LAN.

Yes. Thank you @Ken_Griffiths. Maybe I should give the Orbi a shot?

You need to be able to share the Drive as a network share, not just power the drive, so you maybe best to use your PC/MAC instead, as mentioned in my initial post above.

Thanks. Ill try. Thanks again for you patience 

That’s okay, you may also find this video link helpful too on how to share a folder on a MAC:

https://youtu.be/YVe9Lrz-Zlc