In order to request Master Lists and CRLs from NPKD Service, the client application must first be registered through the Client Manager module. Once a client is registered, different permissions can be set for it within Client Manager > NPKD Service. 

See also

Step 1- Configuring ICAO PKD Upload Settings

Step 2 - Configuring ICAO PKD Download Settings
Step 4 - Using the Service Manager