They ask for a credit card number at the very beginning and say that you're charging you $0 but then when you try and play around with it you get charged suddenly $29.96. I sent them an email asking for a refund and 7 days later, no response.
Developer reply
Hi, our app does not charge users any money, subscriptions, or fees. We have no payment system in the app. Please contact the service or payment provider where the $29.96 charge was made, as we are unable to charge or refund this payment.