A.1 Apple DEP

DEP enrollment fails if the user initially skips applying the MDM Profile on the device

Explanation: While enrolling a device through Apple DEP, if the user initially skips DEP enrollment (if Allow user to skip applying the MDM profile on the device is enabled in the assigned DEP profile) and returns to the previous page to allow DEP enrollment, then the enrollment fails.
Action: To enroll the device, reset the device to its factory settings.

DEP enrollment does not proceed further after specifying assigned user credentials

Source: Mobile Management
Explanation: During DEP enrollment, if the device is assigned to a specific user and the user specifies their login credentials, DEP enrollment might not proceed to the next screen.
Action: Ensure that the user credentials entered are correct.

DEP enrollment fails while re-enrolling a retired device

Source: Mobile Management
Explanation: A device that was retired by another user is now being re-enrolled via Apple DEP. However, DEP enrollment fails after the new user enters his/her credentials.
Action: Ensure that you delete the device object of the retired device in ZCC, before you proceed with re-enrollment.