Try following the steps from their site https://github.com/dompdf/dompdf
//Just pass your HTML in to dompdf and stream the output:
// reference the Dompdf namespace
use Dompdf\Dompdf;
// instantiate and use the dompdf class
$dompdf = new Dompdf();
$dompdf->loadHtml('hello world');
// (Optional) Setup the paper size and orientation
$dompdf->setPaper('A4', 'landscape');
// Render the HTML as PDF
$dompdf->render();
// Output the generated PDF to Browser
$dompdf->stream();