如何使用PHP获取/见解/ page_fans_country /？

I've been really desperate with this problem, I did not find an earlier post/solution for it.

So, the goal is to connect to Facebook (App created, token created, etc.) using PHP and access the /insights/page_fans_country/ of a page. I am able to access my own data with /me, but the access token is wrong for the session and therefore the page_fans_country (that is a public metric) cannot be accessed.

My code is here:

require_once( 'lib/src/Facebook/FacebookSession.php');
require_once( 'lib/src/Facebook/FacebookRequest.php' );
require_once( 'lib/src/Facebook/FacebookResponse.php' );
require_once( 'lib/src/Facebook/FacebookSDKException.php' );
require_once( 'lib/src/Facebook/FacebookRequestException.php' );
require_once( 'lib/src/Facebook/FacebookRedirectLoginHelper.php');
require_once( 'lib/src/Facebook/FacebookAuthorizationException.php' );
require_once( 'lib/src/Facebook/GraphObject.php' );
require_once( 'lib/src/Facebook/GraphUser.php' );

require_once( 'lib/src/Facebook/GraphLocation.php' );
require_once( 'lib/src/Facebook/GraphAlbum.php' );
require_once( 'lib/src/Facebook/GraphPage.php' );
require_once( 'lib/src/Facebook/GraphUserPage.php' );

require_once( 'lib/src/Facebook/GraphSessionInfo.php' );
require_once( 'lib/src/Facebook/Entities/AccessToken.php');
require_once( 'lib/src/Facebook/HttpClients/FacebookCurl.php' );
require_once( 'lib/src/Facebook/HttpClients/FacebookHttpable.php');
require_once( 'lib/src/Facebook/HttpClients/FacebookCurlHttpClient.php');

use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookResponse;
use Facebook\FacebookSDKException;
use Facebook\FacebookRequestException;
use Facebook\FacebookAuthorizationException;
use Facebook\GraphObject;
use Facebook\GraphUser;

use Facebook\GraphLocation;
use Facebook\GraphAlbum;
use Facebook\GraphPage;
use Facebook\GraphUserPage;

use Facebook\GraphSessionInfo;
use Facebook\AccessToken;
use Facebook\FacebookHttpable;
use Facebook\FacebookCurlHttpClient;
use Facebook\FacebookCurl;

session_start();

$app_id = 'MY_ID';
$app_secret = 'MY_SECRET';
$redirect_url='http://localhost/facebook/index.php/';
$access_token = ('MY_ACCESS_TOKEN');


FacebookSession::setDefaultApplication($app_id,$app_secret);

$helper = new FacebookRedirectLoginHelper($redirect_url);
$sess = $helper->getSessionFromRedirect();

if(isset($sess)){
    $request = new FacebookRequest($sess, 'GET', '/me'); // THIS WORKS, GIVES MY PERSONAL INFORMATION!
    // $request = new FacebookRequest($sess, 'GET', '/81221197163/insights/page_fans_country/'); 

    $response = $request->execute();
    $graphObject = $response->getGraphObject();

    print_r($graphObject);
}else{
    //else echo login
    echo '<a href='.$helper->getLoginUrl().'>Login with facebook</a>';
}

So basically the commented request $request = new FacebookRequest($sess, 'GET', '/81221197163/insights/page_fans_country/'); does not work (of course while it is not commented).

So my questions are: