Error when creating a child account

When it asks me to verify I’m an adult and I put in the code texted to me, it comes up with an error message every single time I do it (which has been a lot). And if I click “cannot use this payment method” to try something else, it says “cannot connect” with the option to retry which doesn’t work—no matter where I am or how good my connection is. I have been trying to do this for months. Please help!