Access Denied for User Registration

I'm attempting to have the patreon_user module register accounts with Patreon.

The 'client' on Patreon has the appropriate redirect urls:
https://mysite.com/patreon/oauth and https://mysite.com/patreon_user/oauth

The module throws the error:
Notice: Undefined index: access_token in patreon_get_token()

I added some watchdog code and $tokens is returning:
Array
(
[error] => access_denied
)

I've updated to the latest patreon php library and receive the same error.

I reverted the library, and added a 'scope' variable to get_token in patreon.module:

function patreon_get_token($code, $scope = NULL) {
  $return = NULL;
  $key = variable_get('patreon_client_id', '');
  $secret = variable_get('patreon_client_secret', '');
  $library = libraries_load(PATREON_LIBRARY);

  if ($library['loaded'] && $key && $secret) {
    $oauth_client = new Patreon\OAuth($key, $secret);

    $url = patreon_get_callback_url();
    if ($scope == 'user') {
      $url = patreon_user_get_callback_url();
    }

    $tokens = $oauth_client->get_tokens($code, $url);
    if ($tokens && $access_token = $tokens['access_token']) {
      $return = check_plain($access_token);
    }
  }

  return $return;
}

Then in patreon_user.pages.inc line 15, I modified the get_tokens line:

if ($token = patreon_get_token($code, 'user')) {