disable upload function at checkout page

Hi,
you should achive your goal checking if the user is logged in.

In \lib\class.yith-woocommerce-additional-uploads.php,
search for the method

public function show_upload_section ( $order_id ) {
  echo '<div class="upload-file-section">';
  ...

and change it to:

public function show_upload_section ( $order_id ) {
  if ( ! get_current_user_id () ) {
    return;
  }
  echo '<div class="upload-file-section">';
...

Best regards