Accounts that use single sign-on must implement MFA systems with Authentication Method Reference (AMR) and Authentication Context Class Reference (ACC) claims. This requirement provides the highest level of security between your identity provider and Marketing Cloud Engagement.
Where: This change applies to all Marketing Cloud Engagement editions.
When: This requirement isn’t enforced in the current release. In a future release, all accounts that use single sign-on must meet this requirement.
How: Work with your identity provider to make sure that your system meets these standards.