Follow these simple steps to start using Flatpak
Flatpak is installed by default on Rocky Linux 8 and newer, when installed with a software selection that includes GNOME (Server with GUI, Workstation). If you are using such a system, you may skip this step. To install Flatpak on Rocky Linux, run the following in a terminal:
$ sudo dnf install flatpak
Flathub is the best way to get Flatpak apps. To enable it, download and install the Flathub repository file, or run the following in a terminal:
$ 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!