Hi - as I understand it, you need a key from the person you are connecting to (the one who has the full VST Connect SE or Pro software). They are the ones who are setting up the session, and a key is generated for the ‘Performer’ (you…!) to enter in the Performer app that uniquely establishes a connection to the session.
They can send you notice of the key via email or a txt (SMS message)I guess.
Hope that helps.
Bob