A server stores association between client information and a network device as a management target of a client corresponding to the client information. In addition, the server creates an installer for starting a management function of the network device including client information and distributes the installer to the client. Then, when receiving a validation request including the client information corresponding to an execution of the installer from the client in the customer environment, the server performs validation processing of the client, and subsequently sends identification information of the network device as the management target of the client as a response.