I think whomever you spoke to at Apple Support has wrong information. I am able to copy music to the Watch and I don't have a subscription to Apple Music. It is just that the UI in the Watch app is not appropriately showing what music is on the Watch and also not properly showing downloads etc. I'm using the general release version of WatchOS 9.1I just talked to the apple support (for over an hour) and they said to me it is now just possible to copy music to the watch when you have the apple music subscription...
I also can't copy music to the watch (it is downloaded to my iphone and not in the cloud), the orange circles are just spinning now matter how long I wait.
The automatic downloading of the recent tracks that I've litened too are downloading to the watch but its not possible to do it manually.