In surround mode, the line-in is disabled on any/all Sonos speakers. Get a device with a line-in (move2, Era, etc) and set it up as a new room. Connect to the rca out from the turntable ( check its output) to the input of your speaker via appropriate cable and you’re there. The line-in will show as an available input source for your existing rooms. 

Your setup is not so different from other setups. 

this is what I have posted for others is the past and would pertain to your system as well.

1. The least expensive way to get your turntable integrated into your Sonos system is with your Move… but only if its the Move 2. The Move 2 has a USB C port that can use the Sonos line in adapter so you can connect your turntable to that speaker. if its not the Move 2 then you would need to purchase an Era 100 with the line in adapter. This will add another speaker to your system, but if you have the room it would be a great solution. Plus you can add another 100 for a stereo setup.
2. The next step up would be to add a Port. This will enable you to not need ant adapters and go RCA to RCA. You can configure the Port to automatically play to whichever room you decide on. It's a great and clean way to add a turntable.

Hope this helps.

Thanks for the advice.

My move is the original version, so unfortunately no line in, don’t really have any room for more speakers in the room, so it looks like I’ll be looking for a port.

Found and bought a virtually unused Port on that auction site.  Made up with it, absolutely flawless operation.

Thank you for the advice.