In order to install Google Play Music with GNOME Software, launch GNOME Software,
search for Google Play Music and finally click the Install button.
a Linux terminal emulator,
type flatpak install nuvola eu.tiliado.NuvolaAppGooglePlayMusic and press the Enter key to install this package.
Launch Google Play Music
You should be able to find Google Play Music in a list of installed applications. If not, you may have forgotten
to log out and log in and your desktop environment (Pantheon, GNOME, etc.) has not find out yet
that a new application has been installed.
Alternatively, you can launch Google Play Music from a terminal:
flatpak run eu.tiliado.NuvolaAppGooglePlayMusic