In WPCargo 6.9.1 but default Track shipment using parameter is disable to avoid XSS injection, although in this version XSS is already fixed.

Copy and paste this code to your theme functions.php file

add_filter('wpcargo_can_track_shipment', function(){
	return isset( $_REQUEST[wpcargo_track_meta()] ) ? sanitize_text_field( $_REQUEST[wpcargo_track_meta()] ) : null;
});