Hey there! I just did this through windows so I should be able to help. So, you should see a file in your downloads called "What-Lives-Below-Demo-Windows". You'll wanna right click on that and you'll see an option that says "Extract All..." click that. It'll ask where you wanna put the new file, that's completely up to you. Once it's finished extracting go to the location you put it to (let's say you just had it extract to your downloads folder again for simplicity). Click on the new folder (it'll have the same name as the old one but will be a regular folder instead of a zipped one). Then go into the second subfolder and open the "What Lives Below Demo" application by double clicking. That should open the game. Hope this helps!