RodG:
What settings do you have under configuration->attributes_settings?
Enable Downloads true
Download by Redirect true
Download by streaming false
Download Expiration (Number of Days) 7
Number of Downloads Allowed - Per Product 5
Downloads Controller Update Status Value 4
Downloads Controller Order Status Value >= lower value 2
Downloads Controller Order Status Value <= upper value 4
Enable Price Factor true
Enable Qty Price Discount true
Enable Attribute Images true
Enable Text Pricing by word or letter true
Text Pricing - Spaces are Free 1
Read Only option type - Ignore for Add to Cart 1
RodG:
Does the problem exist with all downloads, or just this one?
As far as I know, it's just this one. But I'm trying it with other folders and I still have this problem.
RodG:
What permissions do you have for your /pub/ folder?
It was 705, but I changed it to 755 and the problem still persisted.
RodG:
What permission do you have on your /downloads/ folder?
It was 705, but I changed it to 755 and the problem still persisted.
RodG:
Although probably not a cause of the problem, your screenshot is indicating that the size of this file is only 152bytes. The just happens to be the size of a zip file that is created when zipping a file with a single character filename with no content (IOW, an empty or unreadable file). Coincidence? Probably not.
Well, I put a blank text file in it. I tried this again with a test.zip file with a bit more content in it and I got the same problem. (I thought the problem might have been numbers in the file name.)