Hello,
You need to include the DOMPDF lib (it's included within the package in the lib folder):
require_once 'classes/TransformDoc.inc';
require_once 'lib/pdf/dompdf_config.inc.php';
$transform = new TransformDoc();
$transform->setstrFile('Text.docx');
$transform->generatePDF();
Note you need to redirect the output of this command to save the PDF:
$ php test.php > Test.pdf
or through ob_ functions of PHP.
And as explained it only returns a good output for very simple documents. The recommended approach is using the conversion plugin.
Regards.