If Calendar Mode (default) is chosen:

Meetings only take place once confirmed by the attendee receiving the request. The request can be made for any time that either person is available and can also be changed at any time.

If Auto-Select mode is chosen:

Meetings still need to be confirmed by the receiver but the time and place will automatically be chosen by the system. If you have meeting places in your event, the system will choose an available time and place for the attendees to meet. To learn more about Auto-Select mode, visit this article.

Meetings are scheduled automatically at the time of booking. If the system is in Calendar Mode (default setting), each meeting will appear in the participants' schedules when it is requested. 

If the request is accepted, the system assigns it to a location and changes the status to 'Confirmed'. If you set the system to Auto-Select mode, it will schedule meetings only if they are accepted.