According to the Symantec Endpoint Encryption Installation Guide Version 11.3.1, one of the prerequisites for the Management Console is the Group Policy Management feature.
If you are using Native policy management rather than Group Policy Objects, you may believe that Group Policy Management is not required.
Symantec Endpoint Encryption 11.3 and above.
Even if you are using Native policy management rather than Windows Group Policy, you still need to install the Group Policy Management feature in order to install or upgrade Endpoint Encryption Management Server.
If the Group Policy Management feature is not installed, the installation or upgrade will fail. An error similar to this will be seen in the msiexec log:
System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.GroupPolicy.Management
After Endpoint Encryption Management Server is installed, you may optionally remove the Group Policy Management feature if you are using only Native policy management but you will need to add back the feature before you upgrade.