Before assigning your device, you need to register it. For more information, see Device Registration.
Every time the first device is added to a new Screens project, a user group is created.
For instance, if the project node name is we-retail, then the user group name is screens-we-retail-devices.
This group will be added as a member of the Contributors group, as shown in the figure below:
Once you are familiar with assigning channel to a display, see the following resources: