Follow these simple steps to start using Flatpak
To install Flatpak on Pop!_OS 19.10 and earlier, simply run:
$ sudo apt install flatpak
$ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
$ flatpak remote-add --user --if-not-exists ramatak https://download.ramatak.com/ramatak.flatpakrepo
Note: graphical installation of Flatpak apps may not be possible with Pop!_OS 19.10 and earlier.
To complete setup, return to the download page, and follow the instructions.!