To install a monitor apparatus module, a monitor apparatus transmits a registration request including a client ID and an initial authentication key included in an installer to a management apparatus. When an authentication key related to the client ID included in the registration request is yet to be issued, the management apparatus issues an authentication key and provides the same to the monitor apparatus. Meanwhile, when the authentication key is already issued, the monitor apparatus displays a screen for input of a ticket issued by the management apparatus and resends the initial registration request with the input ticket to the management apparatus. When the ticket included in the registration request is valid, the management apparatus issues the authentication key and provides the same to the monitor apparatus.