@TechQ, Thanks for posting in Q&A. Before going on, I would explain some information for you:
For Azure AD connect, now it changes name to Microsoft Entra Connect.
https://video2.skills-academy.com/en-us/azure/active-directory/fundamentals/new-name#glossary-of-updated-terminology
Microsoft Entra Connect is an on-premises Microsoft application that's designed to meet and accomplish your hybrid identity goals. So it is not used for iPhone.
https://video2.skills-academy.com/en-us/azure/active-directory/hybrid/connect/whatis-azure-ad-connect
For iPhone, to enroll the user associated device as corporate device, you can choose to enroll with ADE or Apple Configurator (Setup Assistant enrollment).
https://video2.skills-academy.com/en-us/mem/intune/enrollment/corporate-identifiers-add
For ADE enrollment, it is mainly used for the device purchased via Apple Business Manager. And you have Apple Business Manager access. To do the enrollment, you can refer to the following link:
https://video2.skills-academy.com/en-us/mem/intune/enrollment/device-enrollment-program-enroll-ios
If it is not purchased via Apple Business Manager, you can consider Apple Configurator Setup Assistant enrollment. Here is a link with the steps to do the enrollment.
https://video2.skills-academy.com/en-us/mem/intune/enrollment/apple-configurator-enroll-ios
For the above enrollment methods, you need to sign in the user's Azure AD user account instead of admin account. And also please ensure the user has Microsoft Intune Plan 1 license assigned before we enroll device.
https://video2.skills-academy.com/en-us/mem/intune/fundamentals/licenses
Hope the above information can help.
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