1- Create an account using an email and a password of their choice. (on a computer or using the mobile site) you will not be able to register using the app, but once they have created their account they will be able to use the app as normal. 

2- IT IS FREE but you need to enter a credit credit. (the card won’t be charged or kept on file when they register for CLI Studios. There are special privacy rules in the United States that required us to confirm parental consent when a dancer signs up for a CLI Studios account. Requiring a credit card at signup allows CLI Studios to confirm that consent.)

You'll notice on the signup page the following info:

The price for the program is labeled "Free Account / $0.00 per year"