I'm not able to enter their serial number in Apple Business Manager
Hi,
I have a couple of iPhone 8's which have not been bought directly from Apple, and I'm not able to enter their serial number in Apple Business Manager.
All I need is a very low-level management solution - these phones are for employees and will largely be able to do whatever they want. I do, however want to remove the ability the factory reset the device, and I need a solution that if a device is returned to me with a passcode I can easily remove it and re-provision the device for another user.
What's the best way I can achieve this? I have tried JAMF and Apple Business Manager but not getting very far. I also have a MacBook Air which I've set Apple Configurator 2 up on but that isn't proving to provide the solution I need. Unless of course I do have all I need and I'm getting myself tangled up in the multiple Apple ID's, usernames and passwords I've had to create!
Thanks in advance :)
[Re-Titled by Moderator]
iPhone 8