400 Bad Request After Authorization Code

Hi All,
Good Day!
Getting a bad request for request token after a Authorization Code issue.
General Overview for Proof of Concept
So basically, what the application does, is create a meeting on BEHALF of USER ZOOM account. So, I created an OAuth App and follow this link: OAuth for user authorized apps,

  1. it ask permission base on my scope request --working as expected

  2. Once I click Allow it will redirect to my callback url method with Authorization Code–working as

  3. When i try to request an access and refresh token base on the authorization code , I am getting
    a bad request.

Please see code below screenshot

I did try also on postman
Please see screenshot

Thanks in advance