Warning message on order page

-- url of the page with the problem -- : morenadancewear.com.au
-- HikaShop version -- : 3.5.1
-- Joomla version -- : 3.8.11
-- PHP version -- : 7

Hi,
I am getting a warning message (php) on the order page as shown in the attached photo. Any suggestion?
Regards.

Hi,

Try changing the line:
$order_text .= "\r\n" . str_replace('<br/>', "\r\n", JText::sprintf('ACCESS_ORDER_WITH_LINK', $url));
to:
$order_text .= "\r\n" . str_replace('<br/>', "\r\n", JText::sprintf('ACCESS_ORDER_WITH_LINK', $url, $url));
in the file plugins/hikashoppayment/paypal/paypal.php