There could be a couple of reasons, you're seeing a charge. The most common instance is that some theaters add a convenience fee to the purchase.
You may also want to be sure that you haven't added anything in addition to the one free ticket. Concessions or additional tickets will incur additional charges.
If you feel you were charged in error, you'll need to reach out to the theater or ticket vendor directly. Angel Studios isn't handling direct ticket sales. You can find who to contact by reviewing your ticket confirmation email. Usually the ticket vendor will include a link at the bottom of the confirmation email.