Hi, I'm John!
To help narrow down the issue:
- Are you using the classic Outlook desktop app or the new Outlook for Windows?
- What exact error message do you see when you try to add the iCloud account?
If you're using Outlook Classic:
- If you are adding an iCloud email to Outlook, Apple usually requires you to create an App-specific password from your Apple ID security settings. The normal Apple ID password often will not work in Outlook.
- Once that password is generated, you can try adding the account again in Outlook using the iCloud email address: "Add or manage an iCloud email account in Outlook" https://support.microsoft.com/office/add-or-manage-an-icloud-email-account-in-outlook-4aed8b3d-3c68-4743-8973-f6bd1c56e040#picktab=newer_versions
If you're using Outlook New app please see steps in: https://support.microsoft.com/office/add-or-manage-an-icloud-email-account-in-outlook-4aed8b3d-3c68-4743-8973-f6bd1c56e040
If the issue persists, please provide more details by answering my questions.
Click "Add comment" below to let me know.
Regards,
John J.D.