that is a lot, there is no free sites besides google drive, microsoft, amazon and other free storage s that allow you to upload 4.79 GB. Good news is that you can link them to one of them on itch.io but i dont think you can sell it nor you want to do that to sell games. However it's great for free games.
Itch can handle games up to 32 GB. However convincing them that your game is worth that much is going to be difficult.
I suppose that if your game was one the most top grossing games you'd get this no questions asked, but for a new game creator having yet another prerendered CG adult visual novel, aint gonna happen.
If you used the Unity engine you can make a build of your game, then, in the console (top right corner) pull down the menu and select "open Editor Log". Scroll down to the section "Complete build size" and you can see how much space every one of your assets takes in your game. You can then optimize the biggest ones.
Itch can handle games up to 32 GB. However convincing them that your game is worth that much is going to be difficult.
We do not know what their guidelines are for how much space a game is supposed to make. However the 2GB they give out to everyone goes a long way.
No one here can help, I would advice asking for help in Help wanted or offered if you are unable to properly optimize your game size.
