How to add delivery servers for an individual customer?
From this screen, select the number of delivery servers the customer is allowed to add, but also what type of delivery servers he is allowed to add. Once you do this, save the settings and login as a customer. You should see the Servers menu item in the customers area and you should be able to add a new server.
Please note that you also can add a delivery server from backend area and then assign it directly to a customer. In this case, the customer will not see the Servers menu in the customer area but the server will be assigned to him.