Explanation: Users may join devices to Azure AD - This setting enables you to select the users who can register their devices as Azure AD joined devices. The default is All. Additional local administrators on Azure AD joined devices - You can select the users that are granted local administrator rights on a device. Users added here are added to the Device Administrators role in Azure AD. Global administrators, here User2, in Azure AD and device owners are granted local administrator rights by default. Reference: https://docs.microsoft.com/en-us/azure/active-directory/devices/device-management-azure-portal