each night the girls get some experience and you can earn money to build out the club with a bar, dance stage and massage room.
yea, I have enough money, but have only been able to build a bar; everything else is LOCKED.
You haven't met Serena then? She's at the town bar during week nights. If she's not appearing, you might need to start a clean game as something's bugged :/ Her questline will unlock researching new stuff for the club and school.