Tried it on my laptop using edge for the same result. The download produces a jpeg file and not a pdf as it should. Am I alone in that case?
DOH!!!!! PLease excuse me while I find a wall to bang my head against......
As soon as you said it produces a jpg file, I knew what I done wrong (I had incorrectly presumed that I uploaded the PDF, but NOOOOOOOO, I accidentally updated the jpg cover image (which is what shows when you go to DriveThru to download it... sigh.....)
GO redownload, it should give you the PDF now...