Help with Club Arena?

I'm a children's librarian trying to set up an easy way to have the kids play each other online while I spectate. I thought the Club Arena feature would be the solution, but when I try to test it using my personal account and my work account, the event is cancelled automatically when the start time arrives.

I create an unrated club arena with the name "Test," standard game type and setup, 10 min time control, 30 minute duration, no verification required, no minimum games requirement. I set the start time to 5 minutes away, and join with the two accounts. When the countdown reaches zero, the event is cancelled. What am I doing wrong? Do I need more than 2 participants?

Events have a minimum number of participants required to start. For an arena I believe it is at least 4 and may be 5.

Thanks! I thought it might be something like that. I guess I'll have to go without a trial run, but it seems pretty straightforward anyway.

Heres what you should do, help the kids make accounts, then you make a club and then you can make a private club tournament for your kids. I do it in my club all the time. 

Thanks! That sounds like an even better option.