Your QR code was too small to read but that was because you used a screenshot of your level versus using the Export Option within Mekorama. The Export option can be seen in the screenshot above - the right bottom corner with the three circle 'share'. Using this option will give you a much larger / higher quality card where the QR code should be easier to read.
Welcome to the forum. I gave your card a go (after making the QR code larger) and won easily. Not sure why you duplicated the card to have two sides? I generally think a smaller level is more fun to play than a larger one especially when one side is redundant.
