Hi! I suppose you need to unpack .zip archive. You need archivator ZIP if you don't have one. After that you will get Iron Meat folder, and then run Iron Meat.exe inside, no installation needed
Or you can't download game?
(Sorry for my English)
This user might be using the Itch app. I had the same problem. You click download and it presents a dialog with an empty "install" drop-down. I had to download from the web page instead.
(I am on Linux running the game under Wine, so perhaps that's why the Itch app doesn't present any options for installation because the game is technically Windows only?)