Whether it can be installed with the Itch app doesn't have to do with the game itself, just where you upload it to. You have to upload on Itch directly and if your file is too big you have to request a filesize limit increase, something a lot of devs don't seem to want to bother with, which is a shame because the launcher lets us auto-check for and download updates automatically rather than having to keep track of individual AVN pages manually to see whether they've gotten any updates.