After you deploy the Configuration Server, download and copy the registration key file to the Configuration Server. Launch ...

After you deploy the Configuration Server, download and copy the registration key file to the Configuration Server. Launch the installer on the Configuration Server and use the key file to register the server to the vault. Generate registration key file creates a new key every time you click on it and only the latest key is valid at any given time.
After the Configuration Server has been registered, deploy the Master Target Server. Once deployed, log in into the server and register it to the Configuration Server.