There are several existing cards in the database that i just absolutely love, where i'd either made variants for, or simply added more accessories to finish the look. I want to give credit and send the author the card, but i don't want to simply upload and take credit either. Is there an easier way of contacting/giving credit to said author without having to take the credit as my own?

Just create a link to the original card, I think it should be enough in those cases.