Probably 3-5 players and a GM for a traditionally structured game (i.e. some folks getting together in person/on a call and playing a several-hours session), but depending on your organizational structure I imagine you could manage a lot more! I'm pretty confident that the shot for shot structure of the game could handle asynchronous play over Discord or something, which would really open up the field in terms of player counts, though there isn't explicit inbuilt support for it in the text of the zine.