Thanks for buying Super Solitaire!
First make sure you downloaded the mac zip and not the win zip.
Second To install on a mac you should just have to unzip the packaged zip file; do so by double clicking the .zip folder. This will unzip the content of the zip in your /Downloads folder. If you open the .app file you should be able to play it from there.
If you want it to show up in your applications list then drag the .app file into your /Applications folder in Finder.
Also depending on your security settings on your mac mini you may also need to do the following
Again thanks for helping support me, and if you have any other issues let me know. I'll be happy to help you out!