In order to access YouTube Music on the computer etc you have to log into your regular google account. Your phone tablet etc won't sync to the desktop version if you start YouTube music from your YouTube channel. This actually makes sense because YouTube Music now offers you to subscribe to an artist for Music only. If you were to subscribe via your YouTube channel you would have more channels you didn't want to subscribe to that would fill up your YouTube channel feed. So if you start YouTube Music from your main google account you will subscribe to artists on your non channel account.