Put a box around the credit card payment method section (that I used) to contain the entries for that, as initially I wasn't sure wether the zip / post code box was to help confirm the buyer or seller. I was actually wondering if it was needed and looking for an * against it thinking there should be one as how do I know the exact zip code the seller maybe using. Also when I viewed invoice in the payment section Google's download to drive icon didn't appear on my pixel do I had to use Print > PDF

Hope the feed back helps