hello! unfortunately this is a very old project which was developed with windows, which has a different file system from mac and cannot be marked as an executable for mac or linux. if you're willing to, you can try and fix this by using the chmod command on the file QuirkifierFinalBuildMac.app/Contents/MacOS/Quirkifier (and then un-quarantining the app if it gives you a warning.)
i truly don't know if it will work on mac even if you successfully launch it, sorry. also, apologies that sollux was missing! i must have forgotten.