In the Booking Information section, create a password and enter it in the password field and click Save. See Group Bookings - Create Password
The Group Booking can now be accessed through the Group Booking Engine, https://groups.bookingcenter.com/ using the Confirmation # as a User ID and the password you created for the Group. The User ID and password is the same for all guests logging into the Group Booking.
Give the Group Contact the User ID and password and direct them to https://groups.bookingcenter.com/ to log in and start making bookings.