I believe this setting controls if AMT will check for use of credentials before attempting to connect to a sever used for posture validation when using the Endpoint Access Control feature.
Let me get more info on this.
To learn more about Endpoint Access Control, please view the SDK documentation under the topic "Intel AMT Features > Endpoint Access Control > Detailed Description"
Based on the below documentation, I would say it is best to leave this unchecked, unless you know exactly what you are doing:
The Endpoint Access Control (EAC) feature enables a network administrator to enforce endpoint access policies. The Intel AMT device (Releases 2.5 through 8.1) has the ability to integrate into Cisco* Network Admission Control (NAC) and Microsoft* Network Access Protection (NAP) systems.
Note: Beginning in Intel AMT Release 9.0 NAC is no longer supported.