I applied the coupon and the discounted price was shown.
Then I clicked on PayPal Checkout
Once the PayPal checkout popped up I entered my PayPal credentials
I then confirmed the payment for about €17.40 (don’t remember exact price) because it used part of my PayPal balance and the rest from my (valid) credit card.
After I clicked OK I was brought to a Literature & Latten form with two checkmarks and an amount of $0.00 which was confusing.
After than I got a blank page or a page full of BUY buttons (don’t recall which).
So, what has happened? If the sale did not go through I did NOT get any error message, if it went through I did not get any confirmation page or email nor a link to download.