Enrollment Permissions
By default, users in this organizational unit are allowed to enroll a new or re-enroll a deprovisioned device. Enrolling a new device or re-enrolling a deprovisioned device consumes an upgrade. Users can also re-enroll a device that was wiped or factory reset. Re-enrolling a device that was wiped or factory reset doesn't consume a new upgrade because the device is still managed.
Selecting Only allow users in this organization to re-enroll existing devices (cannot enroll new or deprovisioned devices) allows users to only re-enroll devices that were wiped or factory reset, but not deprovisioned. They can’t enroll new or re-enroll deprovisioned devices (anytime an upgrade would be consumed).
Selecting Do not allow users in this organization to enroll new or re-enroll existing devices prevents users from enrolling or re-enrolling any device, which includes re-enrolling through forced re-enrollment.