Sign in error on Outlook on Mac / iOS devices

Scenario

Following Microsoft's implementation of the NAA authentication process, when attempting to sign in on a Mac device (MacOS or iOS) users may receive an unexplained error when attempting to sign in:

Something went wrong. [4s8qj]

You cant get there from here

Reason

MacOS and iOS devices are incompatible with certain legacy conditional access policies which enforce specific client restrictions, such as mobile location or platform type.

The Approved client app Conditional Access Grant can also cause this due to being deprecated, and will result in these errors when used with NAA authentication.

Solution

A global administrator for your company's Microsoft 365 instance must remove these old policies and migrate to the newer application protection policy grant to successfully authenticate with NAA.

For more information on how to complete this, please see Microsoft's documentation linked below:

Migrate approved client app to application protection policy