Joining inside the last 24 hours is binding — you can't simply leave. You
can still sell your spot or give it away, and whoever takes it replaces you.
Earlier than that you can leave; the app confirms first, because your seat may
go straight to the waitlist.
Waitlist: queue when an event is full. If a seat frees more than 24 hours
before the start it is offered to the queue first — the person at the front
hears immediately, and one more player is offered it every hour until someone
takes it. Leave the queue and the offer passes to the next person at once.
Inside the last 24 hours the seat is open to anyone.
Some clubs set their waitlist to fill automatically instead: the first
person in the queue is simply seated.