Family Share not letting me purchase apps or use GC

So my husband and I have the family share, and he is the administrator, and the payment info is his credit card. I was trying to do an in app purchase for a game I was playing, and it wouldn't let me purchase it. It said my husband had to enter his security code. So, he went on his iPad and entered his security code in the payment information and saved it. I'm still unable to make the purchase, it keeps giving me the same message. Every time he goes into his payment information, the security code is not saved.

So, I tried to just bypass this situation and buy a gift card so I could make the purchase. I put my gift card in, and it does show a $15 credit. However, whenever I try to make the purchase, it doesn't give me the option to use the gift card and just keeps giving me the error message. This is so frustrating! Does anyone have a solution to either of these problems?