Doesn't work in the Itch app as the Install drop down is blank, but I think there is a simple fix as I ran into the same issue before. On your game page under "Edit Game" in the "Uploads" section. Check the boxes under your existing uploads for the systems that the app supports (probably just Windows) and then resave your page. No need to re-upload. After about 10 minutes or so, the Install location should be available for the platforms supported within the app. Doesn't seem to require a specific folder layout in the zip as for me (though using Unreal) I have a nested folder and then the main executable is in there, and Itch finds it just fine. You would think for Windows at least it could determine this automatically, but it can't.
Uploads section: