Let me see if I can help you out!
First Check these previous thread's!
Did they help you out?
* If YES
Awesome, enjoy you voice assisted speaker! 😎
* If NO and you have previously had your device connected before to the Google Assistant lets try this next step!
First go to your google home app>click the gear icon (after the page should read "home settings" )>Works with google> Reconnect account and follows steps
(You may see a device connect and add to your sonos device count )
If Reconnect account doesn't work try Unlink account and follow steps
* Now go back to the Sonos app and try to connect the Google Assistant again and you should be good to go!