Here is my postman screenshot.

In response, I am getting a sign-in form. I saved the response in HTML file and it opens like this.

My requirements are simple.
I need to call https://login.microsoftonline.com/{tenant}/oauth2/v2.0/authorize to get the code that is necessary for getting the token.
Then I want to call {tenant}/oauth2/v2.0/token to get the access token
Then I want to call /oidc/userinfo to get the users of AD.
Is anything I am doing wrong?