Hi Viratian, DevTest installers are not found on this Communities site. Installers are accessible at the CA Download site or possibly on a file system within your specific customer environment.
Download DevTest Solutions Installers - DevTest Solutions - 9.5 - CA Technologies Documentation contains more information on downloading and installing DevTest.
You will need either a) a DevTest license key or b) a previously installed and licensed Enterprise Dashboard to specify during the installation.