Issue Generating Refresh Token with OAuth Code Flow

Hello, I have been struggling a bit with getting a refresh token or any success response at all from the endpoint 'https://api.dropboxapi.com/oauth2/token' when following the guide here https://developers.dropbox.com/oauth-guide.

While the docs show all curl requests, I am attempting to make my request currently from postman, but in the end I would like to do this via a standard fetch request if possible.

However, when making requests to the endpoint above, I always am returned the response

{
    "error": "invalid_request",
    "error_description": "The request parameters do not match any of the supported authorization flows. Please refer to the API documentation for the correct parameters."
}

Here is one example of my request:

   var details = {
    'code': 'REDACTED',
    'grant_type': 'authorization_code',
    'REDACTED': 'REDACTED'
  };

  var formBody = [];
  for (var property in details) {
    var encodedKey = encodeURIComponent(property);
    var encodedValue = encodeURIComponent(details[property]);
    formBody.push(encodedKey + "=" + encodedValue);
  }
  formBody = formBody.join("&");

  fetch('https://api.dropboxapi.com/oauth2/token', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8'
    },
    body: formBody
  }).then(function(response) { 
    return response.json()
  }).then(function(data) {   
    console.log(data);
  })

Here is my postman version


For the sections covered in red or 'REDACTED':
The code I am getting via this URL https://www.dropbox.com/oauth2/authorize?client_id=REDACTED&response_type=code&token_access_type=offline

The lowest section is my app key and app secret (in that order).

Is it possible to make this POST request to this endpoint in the way I am trying?

If so, is it possible to see an example somewhere in the docs that is not a curl request? // or point me in the direction of what I am not doing correctly by chance?

Edit: I should also note that this account has purchased 'Teams'.
Thanks in advance!