To add a collaborator, click on New.
You can fill in several information about your collaborator:
Their email, nickname or name in your room, a description (e.g. job title), status, avatar, and the group they are assigned.
Assigning a group to collaborators allows for smoother transitions in the scene builder part of the cloud video control.
Once the collaborator is added, you can send him an email to connect to your room.
Find the page dedicated to the different types of collaborators here.