The Advanced Teams are Tryout based.
It is free to tryout but you must register your child for the tryout.
The Registration is 2 part, the first part is for the tryout and is Free, it will not ask you to make a payment. If/when your child gets invited to join a team, you will be asked to go back in and complete your registration, at which time you will need to complete payment to accept the position on the team.