A flatpak package is available for Mageia 6 and newer. To install with DNF, run the following as root:
dnf install flatpak
Or, to install with urpmi, run:
urpmi flatpak
Flathub is the best place to get Flatpak apps. To enable it, run:
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 Mageia.