Go to your terminal then type Unzip then drag the zipped file into the terminal. It should unzip it and leave the file in your users folder. I had this problem on my macbook with other zipped files before.
Yay! It's unzipped... but when I try to open it I get "The application “Luna_Interficere” can’t be opened." Thanks for trying to help, but I don't know if it's worth it anymore :(
Sorry about that. Mac is a very hard thing to export on. Its not very supported by gamemaker.