Download the zip file listed as "Penguintale - Izanso xd Fight Mac/Windows Download", once you have it installed, decompress it, once decompressed, a folder with the game as well as some other files should appear. Open the game application and enjoy, on Windows it should look like the logo and the character on a black background and on Mac the icon should look like a red heart.

It should be fairly similar to install and play in both mac and windows, except because:

For Mac users. On Mac, your system most likely won't allow you to open the application since it's not from any liscensed publisher, so you'll have to manually allow iOS to open the game via system settings, on the security and privacy tab after trying to open the application and being denied there should appear an option that says "Open Anyway" or similar to that, click that, click open and you should be good to go.