How to install wkhtmltopdf Libraries?
As Pete says, not really a Civi question ... but since it is here:

I think there is a typo in the installation instructions at https://www.drupal.org/project/views_data_export_pdf

The first step reads:


  Place WkHtmlToPdf library under ...


but should be:


  Place phpwkhtmltopdf library under ...


phpwkhtmltopdf provides the php files you listed, not WkHtmlToPdf

Note also that 'scr' in the file list should be 'src'