Up and running in three steps.
Connect
Make sure your Mac is on your Starlink network, by wi-fi or ethernet. The app reads your dish directly, with no login.
Allow Local Network
The first time it connects, macOS asks to allow Local Network access. Click Allow.
Set your location
Your dish does not report its position, so set it once. Use "Use my location" or drop a pin on the map. You can change it any time.