Hope you are well. I have checked that as an admin I can download the file properly. I think it may have a conflict between your plugins or theme. can you please enable/disable other plugins for checking, you may also switch the theme to another for checking. Please let me know then.
There is no issue with downloading the file when you are logged in. The issue is when you are using incognito or not logged in user of the site. I will try what you have suggested. Hopefully, I can track what causes the issue.
Hope you are well. And really sorry for the missing. The topic was assigned by our other Moderator, but the reply was done by me. Now regarding the issue. This page download is working properly from my side,