I don't know about the voting part but if you want to add a contributor go to your game's edit game page and select more then add an admin.
Then you can tick "as a contributor".
It was really interesting.
Can you check out my game too?
Here's my game : https://itch.io/jam/cgj/rate/476685#post-935194
It's called Timeloop. It's about a military designed AI that puts a captain in a time loop.
Let me know if you liked it.