Are you using Windows, Mac or Linux? If you are having issues with the .zip file, I suggest using the itch.io desktop app to install the game. It's the best way to install any game on itch.io.
I tested the windows version by downloading the zip file, extracting it and playing the game. I didn't encounter any problems during this test. I suggest using the desktop app https://itch.io/app to install the game or maybe try using a different program to unzip the file.