OAuth2 Get Access Token Manually like Configure New Token

Use case:
I can retrieve an InforCloud token using the Configure New Token functionality, but I am unable to replicate it manually in a POST request.
Can someone guide me on how Postman encodes the [Configure New Token] requests or puts the parameters in headers or body?

Details (like screenshots):
Successful Token retrieval:

Putting the parameters in the Header or Body results in the same Forbidden response:

Putting the parameters in the Query string returns an error:

I’ve already tried:
This seems similar to this post

Shouldn’t that be in the request body as form data.