I am trying to configure Single Sign On between Salesforce Sandbox and Marketing Cloud Organization following this document.
I receive error message
Provided federation ID could not be found, or the account or user is not properly configured for SSO.
I have checkbox Allow Single Sign-On checked on Marketing Cloud User Id and Federation ID is set on my Marketing Cloud User Id to the same value as Federation Id on Salesforce Sandbox User.
Key Management feature of ExactTarget is activated.