But everytime, when I type : https://account-d.docusign.com/oauth/auth?response_type=code&scope=signature&client_id={my_real_client_id}&redirect_uri=https://localhost:8080/callback

Docusign ask the developer account to sign in, otherwise I cannot get the auth code, so I cannot get the access token by the auth code. So it is not a one time thing, everytime, If I want to call some eSign API, I need to login the developer account everytime, why?