Unable to prove I'm an adult while adding a child account
I'm attempting to add a child account, and after entering the name and birth date, I press "Verify You're an Adult". It brings up the Parental Consent screen, asking for my credit card's CVV. I enter it correctly, but it takes me to a screen that says "Your credit card has expired" (it hasn't). It asks me to enter my password to sign in to update my billing info. I enter my password, press continue, and then the window disappears briefly before popping up again, asking for my password (I know I'm entering the correct password because when I enter my password incorrectly, it shows a "Verification Failed" popup). After 3 of these in a row, it just says "There was an error. Please try later".
My other option is to select "Can't use this card?", which spins for a bit before an error pops up saying "Cannot Connect", with no further actions.
This is my first experience with Apple products and I am not impressed at all.
iPad mini (6th generation)