I have been playing with Milwaukee Sports and Social through their kickball and softball leagues and I am incredibly impressed! It is so organized and professional.
They are doing a 5v5 full court basketball men's league and co-ed league that start in August.
You can sign up as an individual or register a full team. It is legit. Don't waste your time on these boards. Go here: https://milwaukeesportsandsocial.com/collections/available-recreational-basketball-leagues-milwaukee