From what I've seen, phone will not sync to cloud. My plan was to have laptop and RT set to auto download new music and actually download to phone. Got about 10 albums in and realized not happening. RT and W8 laptop will stay in sync as long as cloud symbol is under album, but it appears phone can only be synced from cloud, not to it. I don't know if it is a setting I've missed, just how it is or something MS is working on.
This! Anyway, i have seen posts elsewhere which tells that this work from phone to pc aswell.. Of course no one can tell how, and why it isnt working for everyone..
I have actually been pretty much satisfied with xbox music besides that.. No return to Spotify for me.