Return URL Customisation from Cancelled Order

-- url of the page with the problem -- : afterpay.olstadesigns.com.au/checkout/step-0
-- HikaShop version -- : 3.1.1 [1706191839]
-- Joomla version -- : 3.7.2
-- PHP version -- : 7.0
-- Browser(s) name and version -- : Google Chrome

Hi,

I want to be able to have a popup with "Your payment has been declined or cancelled. Please choose another form of payment" if the cancelled return path is triggered.

Return path: index.php?option=com_hikashop&ctrl=order&task=cancel_order

I have had a look a Display>template>checkout>steps but nothing worked there.

Please help.

Thanks Nicholas, So I have done that and the displays that show are the standard cart displays so how to I ensure that this cancellation popup would be displayed only on a cancellation return to the Checkout?
There is no difference between the pages of

afterpay.olstadesigns.com.au/checkout/step-0
and
afterpay.olstadesigns.com.au/checkout/