登录表单未连接到数据库

Question

I tried out this tutorial here and my problem is that I can't login with an Account. I created a record in my database (username, password etc.) and tried to log in but it didn't work.

I am kind of worried about that part here that it may be outdated:

<?php
 $db_host = "localhost";
 $db_name = "dbregistration";
 $db_user = "root";
 $db_pass = "";

 try{

  $db_con = new PDO("mysql:host={$db_host};dbname={$db_name}",$db_user,$db_pass);
  $db_con->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
 }
 catch(PDOException $e){
  echo $e->getMessage();
 }
?>

Just because there is still MySQL instead of mysqli... Could that be the problem? I neither have any logs nor errors and my provider is Nitrado.