huh thats odd, yah i was just using the OSX unzip but i just tried the .zip program and got the same result.
well i bought it as part of a bundle so i'm not mad or anything.
Viewing post in PixaTool 1.55 Released !!! comments
Have you tried this fixes for OSX ?
https://itch.io/t/294367/problems-to-run-on-macos-check-this-solutions
Also check what this guy said about OSX version:
He used a extractor from appstore that worked. Is OSX giving you any kind of error? Without feeedback, screenshot of what happens i can't help too much