During Installation and device configuration, on 'Link Child' screen, there is a button labeled 'Create Child's Profile' to create a Child Profile.
Link Child Screen during installation and device configuration
When you pick the 'Create Child's Profile' option you will see the 'Create Profile User' screen
Create Child's Profile
Here you need to provide your desired child name, birth year, and gender. After providing the information, hit the 'Create' button. This will create a new child profile as shown in the figure below.
Link Child Screen during installation and device configuration.