How to make a proper OAuth request to Dataverse API with Postman?

I want to make an OAth request to the Microsoft Dataverse API to get the Bearer token, and with this token I wish to make authenticated requests to PowerAutomate. I use Postman for making the requests. I can get the Bearer token in 2 different ways, but with the same result after using these in a request: 401 Unauthorized
My settings:
Common auth url:
Auth url with TenantID:
As you can see I got a Bearer token for both, but when I try to call the simplest /WhoAmI endpoint I got 401 Unathorized error.
I have my API permissions set up properly in the Azure app:
I have my application user with the right application ID:
My first question: What am I missing? What else should I set up?
My second question: What is the difference between the two auth endpoint I am using?
Any suggestions are welcomed.