Hi,
Looking at the checkout on that website, I can see that they actually removed the whole checkout and use PayPal Express Checkout so that the checkout happens on PayPal. You can do that too with HikaShop:
- remove the views from the "checkout workflow" in the HikaShop configuration to leave only the "cart" view.
- hide the finish button with CSS
- configure the PayPal express checkout payment method via the menu System>Payment methods and activate the display of the button on the checkout.
That way, when a customer access the checkout, he will see his cart with a PayPal express checkout button to finish his order, similar to what is on that website.