For file upload to work successfully, the forms encoding type must be set to multipart/form-data:
<form action="applicant.php" method="post" enctype="multipart/form-data" name="Default_SouthernPolymerCSS_SPCSS" class="SouthernPolymerCSS_SPCSS" id="Default_SouthernPolymerCSS_SPCSS">
If you are still having an issue, remove the redirect to the thankyou.htm page form the universal Email server behavior, then on the bindings expand the WA Uploaded File Global Status and drag the Debug info binding to the page, this will give info on the status of the file upload.
Also add the following at line 1 to see if there are any PHP errors occurring:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>