This means that the venue only takes in a very limited amount of people. Mostly 30-50, which means that if you arrive late, you can end up in a long queue.
Only if it says "Exclusive".
Most of the time there is free entrance.
Keep it simple, come as you are.
Invite us to your next gig, and show us your skills, then we let you know.
If your request gets approved, you may find your invitation in your junk mail folder. Make sure you do not block exclusive [at] vibecrib.com, but make it a trusted sender.