I can't play the game :'
Maybe try to add the other files that Unity provided when you build the game
That's fine, there's always a time to learn. XD
For Unity desktop version, it's usually these files :
For Unity HTML 5 version, the files are these :
Compress those files into zip/rar then upload it.
Fore more details about uploading an HTML5 game, you can check this https://itch.io/docs/creators/html5
You can also check this http://wiki.compilgames.net/doku.php/gdevelop5/publishing/publishing-to-itch-io