Trying to obtain access token gives 401 access denied error

Hi Everyone,
I am trying to access mydomain.oauth/token to obtain the access token and getting 401 access denied message from my website in Sitecore using Asp.net MVC (using Owin QuickStart quide from Auth0).
I tried from a console app and it works fine. I have the correct client id, client secret, audience, and following this guide.
Get Management API Access Tokens for Production
Any insights or advice would be greatly appreciated!

The answer is here: Claims doesn't have all the user information

summary: I had to call the API Explorer Application (Machine to Machine) with the relevant client id and secret, not the regular web application.