Using Postman with Oauth2 site

I am trying to send commands to my oven and similar through this site:

I am struggling with the authorization though, as far as I understand I need a webserver for the redirect uri, if I am using the site directly to get the token, so I am trying with postman. When i Try to use postman i get the message: {“message”:“Not found”}

I click on the "get new access token, on the authorization page (after choosing the type Oauth2.0)

In the window i have filled in the following data:

Token Name: Miele
Grant Type: Authorization Code
Callback URL: [Empty]
Auth URL:
Acceess Token URL:
Client ID: [my client id]
Client Secret: [my client secret]
Scope: [empty]
State: login
Client Authentication: Send as Basic Auth header

Any help is very welcome, my skill in this is pretty limited.