The application username is not an input that is required when you install Cisco Unified CCX. The application username is the username that you use to log in to the Cisco Unified CCX Administration web interface after the installation is complete. You can configure the application username during the initial system setup, which is a separate step from the installation. The other inputs, such as the platform administrator username, the IP address, the default language, and the time zone, are required during the installation process. You need to enter these inputs to configure the basic system parameters and network settings for the Unified CCX server. References := Cisco Unified Contact Center Express Install and Upgrade Guide, Release 12.5(1) SU2, Deploying Cisco Unified Contact Center Express (UCCXD) v6.0 Course Outline