I see no way of registering as a team for this game jam. Are only individual submissions allowed, or can we participate as a team? If so, should both of us register here, or only one?

I think that itch.io doesn't support teams that well, but when you submit the game, you can state that another user collaboted with you. So both people should register, or at least have an account in itch.io. 

That said, teams are allowed, but we only have one prize :-)