Well, I waited about an hour then tried again. Then i searched google for help. I used Construct 3 to make games on Itch. And you might not believe it, but i also used Scratch.
Viewing post in What games can i use to publish on itch?
Im not sure if it was really an error because i didn't get any message. I uploaded it this way: Dashboard> Create new project> Upload file(s). I tried to download the game for myself and it was a c3p file. I opened it and Windows asked if i would like to use chrome to open the file, or Microsoft store.
Well, if you can't figure it out, ask in General Development. But the export command shouldn't be hard to find, it's pretty important.