I noticed on the prizes page it only shows prizes for 12 team leagues. Also in trying to create a league that’s not 12 teams it looks like there is only a free league option. Are only 12 team leagues eligible for prizes?
Yes, you have to have a 12 team to qualify for prizes.
You could always do a $20 league with a side bet on LeagueSafe. I’m aware of a few leagues that do that.