Hi,
What you can do is copy the content of the file "order / invoice" in HikaShop > Display > Views (backend template) to the view "checkout / after_end" (frontend template).
By this way, you will have the invoice display in the view called after the payment. You will have to edit the variables, all the informations should be stored in the object "$this->order";
Else you can change the return url in the plugin configuration to redirect to the view displaying the order of the customer (via a menu user control panel).
Or add a redirection in the page "checkout / after_end" to redirect to this same page.