BEFORE PROCEEDING, PLEASE ENABLE RTMP DESTINATIONS INSIDE OF LIGHTSTREAM LABS. MORE INFO AVAILABLE IN THIS ARTICLE.
To obtain the information for your scheduled event, you'll want to visit your YouTube Events page and create a "New live event". Once you've created your event, select a stream key type from the following page and you'll see the Ingest Server (Primary Server URL) as well as the Stream Key (Stream Name)
You'll then want to import this information into an RTMP Destination as shown in the gif below: