How to always allow OSX Safari downloads when there's no domain to add?

I'm using a web service where the interface is a local file (an html file and associated data folder), which sends a data request to a server, which then sends files to download.

No problem if using Brave, etc., but if I use Safari (and there are some reasons to do so) I get a download confirmation prompt every time. But I can't whitelist the site because, as shown in the attached pic, there's no domain name to select in Settings>Websites>Downloads

Aside from whitelisting all websites, is there a way to download without a confirmation prompt?