You not only have to post the Unity launcher for the game but also all of the files.
I've posted an image for the game Milkman Karlson, so you can see the kind of files you need to submit. To do this, you have to zip them into a file and submit that. I hope this helps, and I'm excited to see what you've created!
This is Milkman Karlson if any of you are interested: Milkman Karlson by Dani (itch.io)