I love this game, just like to point out that there is another error (ha) on mac where you get "The application "ERROR143" cannot be opened".
However I also figured out the solution: Instead of using the inbuilt Archive utilities to unzip the .zip file, right click the .zip file and unzip with the Unarchiver. You'll probably get the “the developer cannot be verified.” error but you have instructions for that already in the walkthrough doc, and woo, you can finally play on mac.