Android 7 is no longer actively supported by Sonos: https://support.sonos.com/s/article/4779?language=en_US
 

The Roam will have to be set up on your Wi-Fi using the Sonos S2 app on a phone or tablet before you can use it. Because Android 7 is no longer actively supported, it may not allow you to do a software update on the Roam during the setup process.

The behaviour may depend on the exact release you are running, but on my Android 7 phone, the app will not let me do other things than the one you describe. So for example it will not allow me to initiate a scan of my music library - even though the phone app plays no active part in the scanning process - or to add a voice service, or another music radio station, or to change audio compression settings, or to change any of the network settings, or to Transfer System Ownership. This is a subset of the things Sonos won’t allow you to do any more from your phone.

So be warned - the app has been deliberately crippled for users of Android 7 and earlier.

You would need to get a hold of a supported mobile device to do setup  You can’t use a PC or mac.  Once you are setup though, normal playback operations can be done on Android 7.

And am I correct in thinking that I cannot “S2 v13.0 Sonos Controller for PC” either?  I can’t see any “add device” options there, diasbled or otherwise!

Looks like I’ll have to buy a new phone!   Hah!  Thanks a bunch, Sonos.

I know where I stand now. 

Thanks all

Alan

Sonos follows Google in stopping support for certain OS versions. Your first complaint should be aimed a Google. Though I have to admit Sonos seems to follow Google a bit closer than some other manufacturers.