Sorry, iOS devices cannot be added at this time.

It seems that you are encountering an issue with adding iOS devices, which can be related to several factors. Microsoft Intune requires specific configurations and certificates to manage iOS devices effectively. If you see a message stating that iOS devices cannot be added, it could be due to:

1. Missing or Invalid APNs Certificate: The Apple Push Notification Service (APNs) certificate must be valid and properly configured. If it is missing or expired, device enrollment will fail.
2. Enrollment Policy Issues: There may not be an enrollment policy set up for iOS/iPadOS devices, which can prevent them from being added.
3. Device Limitations: If there are already too many devices enrolled under your account, you may need to remove an existing device before adding a new one.
4. User License Issues: Ensure that the user has the correct license type for mobile device management.

To resolve this, you can check the APNs certificate status, ensure that the enrollment policies are correctly configured, and verify that the user has the necessary licenses and hasn't reached the device limit.

For more detailed troubleshooting steps, you can refer to the resources available in Microsoft Intune documentation.

You can't register an iOS device in a Microsoft account; that is correct.

However, you can install the Office apps on an iOS device if you have a subscription. See https://support.microsoft.com/en-us/office/set-up-office-apps-and-email-on-a-mobile-device-7dabb6cb-0046-40b6-81fe-767e0b1f014f .

If you don't have a subscription, you can use the free Office apps on your mobile device.

P.S. Registration is for Microsoft hardware such as Surface laptops.