Hi there,
It seems your having issues with the Apple’s Mobile Device Management (MDM) enrolment screen that appears when a device is linked to a company’s management system. Since you no longer work there, the phone is stuck in the company-managed setup, and you can’t bypass it in the normal setup flow.
Erase the iPhone Completely
You’ll need to wipe the device and set it up as new.
Using Finder / iTunes
Connect your iPhone to a Mac or PC with Finder (macOS Catalina+) or iTunes (Windows/macOS Mojave or earlier).
Put your iPhone into Recovery Mode
How to Enter Recovery Mode
iPhone 8 / X / 11 / 12 / 13 / 14 / 15 / 16 / 17 /
Press Volume Up + Volume Down + Hold Side button until recovery screen appears
iPhone 7 / 7 Plus
Hold Side + Volume Down until recovery screen appears
iPhone 6s & earlier
Hold Home + Top/Side button until recovery screen app
Feel free to leave a reply if those steps don’t work.