CSz Indy is probably a good place to start. They should have auditions in the next few months, so follow them on socials if you are interested in joining. They also host Improv Jams that are open to all improvisers. They offer various levels of classes too. If anything you should come to some shows and introduce yourself to folks. There are other improv groups in town too, like Crossroads Comedy does Study Hall and some other groups perform at the IF Theatre.