Tryout would mean an animation test around what the event will be about if you’re participating for example if it’s Hockey event you would upload a short animation not many frames showing an overall gist of you’re animation skills where only the best out of the bunch will be pick (let’s say the set number is 10 and 20 tryout I would then have to pick the 10 best)
However you can also be involved not as a participant but can join up as a Co Promoter/Co Manager of an event or a third party role in the event like being A Referee or someone who interviews players on that team