There is nothing to refund, because nothing is sold
Every card is free and there is no checkout. This page exists so that the policy is written down before anyone could need it.
Today
Free means free
Nothing on this site has a price. The packs are a free download behind one email field, and what you download is yours to keep, with no expiry, and corrected versions of those cards appear at the same download link, free.
If a card was wrong, tell us at the address on the contact page. The correction gets logged in the changelog with a date.
If that ever changes
The policy, written in advance
If anything is ever sold here: thirty days, no questions, and you keep the files — there is no way to take a downloaded image back, and pretending otherwise would be theatre. A refund process that asks why is designed to talk you out of it.
Any change to that is logged in the changelog first. See how cards are checked for what would have to happen before anything is sold.