Sure, thank you.
- I downloaded the Mac.zip archive from the site.
- Unzipped the archive, which creates a folder Mac in which Mac.app is.
- Double clicked the app, leading an unhelpful "The application “Mac.app” can’t be opened.".
I also tried the CLI command "open", right clicking and choosing open from the menu (which offers alternatives sometimes). Last, I also put the app in the Applications folder, but no change.
Running on the latest MacOS to date (Catalina). The app was compiled in July last year, and the OS released a few months later (not sure). Would that be related?