In order to install Emby with GNOME Software, launch GNOME Software, search for Emby and finally click the Install button.
Then log out and log in back to let your desktop environment (e.g., GNOME Shell) find out that a new application has been installed. Otherwise, you may see mismatched application icons and other funny bugs.
Alternatively, launch a Linux terminal emulator,
type flatpak install nuvola eu.tiliado.NuvolaAppEmby
and press the Enter key to install this package.
Then log out and log in back to let your desktop environment (e.g., GNOME Shell) find out that a new application has been installed. Otherwise, you may see mismatched application icons and other funny bugs.
flatpak run eu.tiliado.NuvolaAppEmby