Configure > Meeting settings > Group Meeting Types

This tab only appears if you have enabled it in the General Meeting Settings tab.  (see help)

A Group Meeting in this context is a structured  meeting type that is intended to allow Attendees to join a meeting that other Attendees are already a part of.   This is not the same as an ad-hoc group meeting that a moderator might create from the Meeting Times page which puts two or more Attendees into a meeting together based on the Moderator's discretion.  The feature discussed here allows Attendees to join it themselves.

They will be able to join either as automatically confirmed, or as just a request awaiting the approval of the host party.  For example, a Demo session at a Trade Show might welcome all-comers and require no approval. A dinner or reception, on the other hand, may  require a screening process so that only the best 10 requestors get to attend and be approved.

To create a Group Meeting Type - simple click the Add button and give it a label.  Then click Submit.  Once created it can then be deployed by the Admin, as desired - by assigning it to specific times slots for specific Attendees/Companies - from the Meeting Times page.(see help)