Follow these simple steps to start using Flatpak
To install Flatpak, run the following in a terminal:
$ su # inary it flatpak
Flathub is the best place to get Flatpak apps. To enable it, run:
$ su # flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
To complete setup, restart your system. Now all you have to do is install some apps!
Note: graphical installation of Flatpak apps may not be possible with SulinOS.