Send delivery note by email

Sorry, no, it is a HTML page that can’t be attached to the email. But you can include the print link. Try something like that in your functions.php (not tested):

function my_print_link_in_emails($order, $sent_to_admin, $plain_text) {
echo '<a href="' . wcdn_get_print_link( $order->id, 'delivery-note' ) . '">Print Delivery Note</a>';
}
add_action('woocommerce_email_after_order_table', 'my_print_link_in_emails', 10, 3);