To install the Flatpak system package. Run this command in terminal:
sudo apt-get install flatpak
Next, add the Flathub repository (there is only a space between ‘flathub’ and the URL, not a new line):
sudo flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
Finally, you have to restart your Chromebook. Now you can download any app found on Flathub. Most of these apps are available through the Software Center or as a .deb file, but there are a few exclusives.
Flatpaks are only installable through the terminal on a Chromebook. Every app on Flathub has command line instructions at the bottom of the page. For example, this is the command to install the Slack desktop app:
flatpak install flathub com.slack.Slack
However, you have to add “sudo” to the beginning, or it will fail in terminal. So what you actually have to run is this:
sudo flatpak install flathub com.slack.Slack
After everything is downloaded and installed, the app should appear in the Chrome OS app drawer.
ChromeBooks 