The FriendNet client is stored in a single executable, and can be updated simply by replacing the file.
You can find the latest version of the client on the download page.
If the client is currently running (in the background or not), shut it down by clicking the red button on the top right
of the web UI. Once you have done that, simply replace the old friendnet-client-*.exe (or friendnet-client-* on
other platforms) with the new one. You can now run the client again to start the new version.
If you installed the client through the .deb package, download the new .deb and use dpkg -i to upgrade.
If you installed the client through the AUR package, upgrade it using your AUR package manager (such as yay or paru).
Next: Using with WebDAV