im pretty sure roblox isn't compatible with itch.io. I think you'll have to teach him the basics of Unity or Unreal Engine(or whatever you use). If it is, great! Good luck!
You won't be able to upload a build to itch.io, but you are allowed to use any game engine or framework
If your friend wants to use roblox studio, they could always upload a game to itch without any downloads, and just have the link to the game in the description.
