ok, so the only way to add cards to the game and get it to recognize them is by adding them directly into the TabletopClub/cards directory where the original assets are being kept. I've tried adding the custom asset pack into various areas to no avail. It does not recognize any directories outside of the TabletopClub main directories, I followed the tutorial to the letter. Also if you do get this bug fixed, it would be much easier for a user, to click an executable and have a bunch of images in a directory made into a 'stack/deck'.
This is for the windows 64 bit version.