Each policy is assigned to certain groups of users or groups of devices, therefore each device receives a policy settings pre-defined to its group assignment. Devices not being members of any group and groups not being assigned to any policy receive a policy of the lowest priority (policy being at the bottom of the list). Devices being members of several groups receive the policy of the higher priority. 

In the Assigned Groups tab administrator is allowed to assign groups to the policy. In order to select the group click on the Add device group or Add user group button. Popup with group list will appear.

Mark checkboxes next to appropriate groups and click Select. Groups will be now assigned to the policy.