Steps to reproduce:
I'm not exactly sure. I am unable to download a file using "Download Linked File" from my developer page on https://addons.mozilla.org. I can "Download Linked File As" just fine. I have two versions of an extension on the developer page; neither work.
I can download other files just fine, for example I uploaded the same file to the extension's GitHub repo, and I can download it from there.
"Download Linked File" works
Orion and macOS:
Orion Version 0.99.108.1.2-beta (WebKit 613.1.12)
macOS 12.0.1 (21A559)
Also tested on Version 0.99.109-beta (WebKit 613.1.12)
Compatibility mode on.
Because this was so strange, I created a new user on my laptop to test with a fresh install. Same issue with those files on the developer page.