Use the following snippet to add the order notes to your Prints
function sl_cc_printus_extra_template_data_270224($extra, $order, $template_name){
return $extra . '<br/><strong>Order Note:</strong> ' . $order->get_customer_note();
}
add_filter('printus_template__extra_data', 'sl_cc_printus_extra_template_data_270224', 11, 3);
The printus_template__extra_data
filter can be used to add other custom data to the prints.