Thank You for working with me. There is no information about getting a refund at the 'contact support' link.
Actually, they said on the 'more information' link:
If a seller wants to issue a refund, there currently isn't a place in their dashboard to do it, they'll need to contact us to initiate it (please provide a purchase ID).
So it seems that you, the seller, must contact them.
Of course, I never used the game because I could not download it on my mac. It has been years since I ordered a game for my Mac on a site that was not specifically a Mac site and it just did not occur to me to check this before I made my order.