If you were trying this Sunday, the Church systems seemed to be having major access problems. Try again today or sometime during the week, you may be able to get past that point now.
I do find it interesting that there is a prompt about age, since if you're logged onto the Church account, the Church should automatically know the age of each logged-on member! Ideally it would internally query the member account info and determine age validity for donations, without requiring an interactive prompt.