You can use one of the Live Stream API quickstarts to set up a test live stream. Both HLS and MPEG-DASH live streams are supported. This procedure is optional; you can use your own live stream in place of this test live stream.
The Live Stream API quickstarts use Application Default Credentials for authentication, but you can use the service account you already set up in Before you begin. For this option, make sure the service account has the Live Stream Editor role.
Make sure to keep the live stream active; don't follow the steps in the Clean up section until you are done with the live stream.