The devices were not in ADE, but they are now. Meraki support said the error code was due to the device already being enrolled. The issue was my misunderstanding: I attached the management profile from the add devices page when what I needed was a PayLoad WiFi Profile to attached to the setup in Configurator. I've successfully enrolled my test devices into supervised mode. The really cool feature is iOS 11+ devices can be added into an existing DEP account through Apple Configurator on macOS, even if it was not purchased from Apple or an Apple reseller. For steps on how to do this, see https://documentation.meraki.com/SM/Device_Enrollment/Enrolling_and_Supervising_iOS_Devices_using_Apple_Configurator_2.5_or_Later#Manual_Enrollment_-_Add_device(s)_to_Device_Enrollment_Program_(DEP) ... View more