Hi, Hobo Joe, here's what's going on:
Your zip file has been moved to https://bmrf.me/download/BMRF-Progress.zip
When you access the file through the browser, your browser receives the 301 code and then automatically downloads it from the new location. When the launcher attempts to download it, we download the "document has moved" HTML page that has been served and then attempt to open it as a zip file, which fails. I hope this helps!