An AppDynamics deployment consists of multiple agents to monitor different components of your application environment.
Only if the license is valid, you can download Installers for each component such as Agent and Controller. the Controller is the component that monitors the data received from the agents and can be provided either as an AppDynamics-hosted SaaS or installed on-premise.
For most types of agents, you can use the Getting Started Wizard in the Controller UI.
If you don't have the license, you can start your free 15-day SaaS trial now, easily, with no credit card required. However, it is Saas. Please download the data from the following URL.