Yeah, that makes sense. Sorry about that! It is something a lot of people assume.
Usually specifically solo games like to advertise that, so it’s pretty safe to assume if it doesn’t say it’s a solo game specifically then it’s not. That is definitely with this game! I would say this game is for 3 to 6 players, and that would include a GM.
As for play time, that would be hard to pin down. It’s an open ended thing. Its plausible that a group could play for 20+ sessions, although I would suspect the average group to get 5-6 sessions out of such a simple game. I hope that helps!
And welcome to the hobby!