Amazon PSN card buy errors?

I just wanted to buy a 15 euro PSN card with my remaining Amazon credit. Since I'm doing this for the first time, I had to confirm my age. So far so good at the payment process, I have indicated that my Amazon credit to be charged but in the next window is: Select a billing address
We need a billing address that we can associate with your payment details. Please select an address from the address book or enter a new address. Do not worry, this process is only necessary once for each credit card. If you contact us about your order, we will only refer you to the name of the account you entered below.

Note: When you purchase on account, the address used there will be permanently stored on your first order on invoice. Changes to the address for purchase on account can then be made only by changing the address marked as "Billing address". Any exchange with addresses from your address book, even the same, is not possible here. In addition, your delivery address must be your home address and match your billing address.

Will an invoice be sent to me now or something? I mean, I have enough credit on my account. Not that I still get a bill there?

Normally this will be deducted from your account. It could be that they send you a receipt there but you have to pay nothing more.

You will not be billed. I do not know exactly why but if I ne PSN card or just order the code I have to specify the data synonymous every time. The credit is used quite normally and that's it.