Q: to download shared content, your family must have a valid payment method

Hi Mel3b,

I'm sorry to hear you are having these issues with Family Sharing. If you are getting the "valid payment" alert message when you alreadyt have a credit card on file, you may want to try re-entering the card details on the account, even if you know they are currently correct. You may find the following article helpful:

Family purchases and payments - Apple Support

Regards,

- Brenden