Do I need to host it in another website, or can I do it in itch?
Like I could have a folder inside my zip file which I upload here with the name 'User Saves' and whenever I see a user with that id enter, I could load a file containing their progress
Itch doesn’t host databases or servers for you. You can do it with whatever method you wish (using a VPS provider or hosting your servers at home).
If you only need to store & load this information locally (aka it doesn’t transfer through the internet automatically) then a database isn’t necessary.
