A leader from the chapter you asked about calls you. No deck, no pitch. You talk about what you're building and what's missing; they listen.
They tell you plainly whether this is the right room for you. If it isn't a fit, you'll hear that — it's a short conversation and nobody's time is wasted.
If it looks like a fit, you come to an event before anyone asks you for anything. You won't stand alone at the door - someone will be expecting you and will know who you should meet.
You've met the room and the room has met you. If both sides want it, you're invited to join your chapter, and your leader walks you through the commitment and the numbers.