When the Instant Join app is enabled for an organizer's account, then all attendees who join their sessions have the option of joining via the Instant Join app. When it is disabled, attendees must join using the desktop app or mobile apps.
Organizers can check to see if the Instant Join app is enabled by logging in at
in the left navigation. On the Instant Join tab, check or uncheck the
Enable Instant Join for attendees
Note: If you are an attendee joining someone else's session, then it is up to the scheduling organizer of the session to enable the Instant Join app for the session (even if you are also an organizer yourself).