Premium subscribers can create their own private critique group. One of the members creates a queue (Story Queue — My Queues), and invites the other members to participate. Before creating the queue, members have to decide on issues such as how long each critique period lasts, if it runs on the CC credit system or not, etc.
All premium subscribers can create their own queues, but it's simpler for a crit group to use one queue for their shared work. If they prefer, they can instead each submit their stories to their own personal queue, and invite their group members to that queue.
This use of the Private Queue system only allows for Premium Subscribers to be members of the Queue and you can invite a maximum of eight members into each "Private many-2-many Queue". If you wish to have more than 8 members, you must become a Gold Premium member.