The server code is hidden inside your address
The server code a DİA connection asks for is not a separately issued number but the subdomain of your service address. Whatever your address looks like, the first segment is exactly the value to enter. Someone unaware of this ends up requesting a separate code from DİA and waiting.
Two more things shape how long setup takes. First: the connecting user must be defined on the DİA side with the relevant service permissions — an ordinary user account is not enough. Second: the API key is not generated from a panel but requested from DİA by email. These two are the waiting steps of the setup and may not complete on day one.