Unable to sign-in to Settings>General>VPN & Device Management > Sign-in work or school account

I'm Smartphone admin and i wanted to setup BYOD device remote management enrollment using "Sign-in with work or school account". However, when i try this with my personal apple ID, error shows "Sign-in Failed. Your Apple ID does not support the expected services on this device. Contact your administrator to sign-in."

Other way around, tried using my company Apple ID (Which is my company email address enabled) and getting different error while sign-in. Error shows "Sign in failed. The account being signed-in to already exists and cannot be used again."

Need guidance to proceed on this query.