GNOME Music is a crippled feature-less unusable music player for the Gnome desktop environment which will only work in that specific desktop environment.
Features and usability
Starting Gnome Music presents this window:
The only thing you can click in that window is the blue "Music Folder" link. Doing so launches Thunar in the Xfce desktop environment; the default file-manager will be launched in other desktop environments. You have to use Gnome to configure your music folder.
Launching it in Gnome improves it's features from being able to show a window but not by much.
All in all it's the worst Music Player made ever. It is just not usable for .. anything. Perhaps they were trying to make it feel like GNOME Videos - which is the worst video player of all times. Still, it is better than GNOME music since it's possible to (barely) use it on all desktop-environments.