OAuth2 Failed using posman

I created OAtuh2 Client at ERPnext

and tried to get
http://localhost:8080/api/method/frappe.integrations.oauth2.authorize?state=444&response_type=code&redirect_uri=https%3A%2F%2Foauth.pstmn.io%2Fv1%2Fcallback

but i get Error: connect ECONNREFUSED 127.0.0.1:u6e80:

can anyone help me how to setup OAuth using posman?

Did you try this already?

i using
ERPNext: v12.16.2 (version-12)
Frappe Framework: v12.13.0 (version-12)

what i want to do is after client login, it return a login form and OAuth2 to authenticate the user.
After that, exchange the token for Authorization Code Grant with ID Token.

I read through this
https://frappeframework.com/docs/user/en/guides/integration/rest_api/oauth2
but seem like i not yet found a solution