Starts at Stadium races are different from normal Spartan Race races.
Two departures SAS will be present. The first will be a SAS call waves initially scheduled every 15min.
Once inside the call SAS, participants will be invited to advance to the departing SAS where departures every minute will be set up. 20 people will be called every minute to take the start.
If you run as a team no worries. You can go on a wave and join your team later, try to find you in the two SAS with your teammates.