The map is updated by a client that every player runs. It captures the position traffic the player is sending to the server and sends this on to the web frontend for the map.

Once there, the position data is stored in a database, where it can be used to render out player positions and be used to define roads, tunnels, areas and points of interest.
Because the data acquisition is performed on the client side, there is no need to change the server configuration at all. The system could be used on a server without the admins knowledge.