PHP use keyword is causing 500 server error

I'm trying to implement PhpPresentation to convert some files, so I have the following code:

use PhpOffice\PhpPresentation\src\PhpPresentation\PhpPresentation;
use PhpOffice\PhpPresentation\src\PhpPresentation\IOFactory;
use PhpOffice\PhpPresentation\src\PhpPresentation\Style\Color;
use PhpOffice\PhpPresentation\src\PhpPresentation\Style\Alignment;

For some reason exactly this piece of code is causing 500 Internal server error. I have error reporting set to all, but no errors are shown. The path is right, i have the PhpOffice folder in my root directory(public_html) and the corresponding subfolders too.

autoloader code is loaded this way:

require_once 'PhpOffice/PhpPresentation/src/PhpPresentation/Autoloader.php';
  \PhpOffice\PhpPresentation\Autoloader::register();
  require_once 'PhpOffice/src/Common/Autoloader.php';
  \PhpOffice\Common\Autoloader::register();