Download, run the installer, sign in. That's it.
Download SyncPointWindows only, for now. Your browser or Windows may show an "unrecognized app" warning for a new download like this - click More info → Run anyway to continue.
Double-click the downloaded file and follow the setup wizard - installs SyncPoint properly and adds a Start Menu entry (and, optionally, a desktop shortcut).
Use the same email and password you signed up with on this site.
Press Ctrl+Alt+G over any game to open the panel. That hotkey always works, even if you set a custom one later in Settings.
Prefer running it from source instead? Download the source (.zip) - needs Python installed.