Add to cart botton not redirect

-- url of the page with the problem -- : www.mangialarossa.com
-- HikaShop version -- : Essentiel 3.1.1
-- Joomla version -- : 3.7.4
-- PHP version -- : 7.0
-- Browser(s) name and version -- : Firefox

Hi, when I click on add to cart bottom, nothing happens while before the upgrade to version 3.1.1 it redirected to checkout. In Configuration>Advanced settings, I selected yes for 'Use AJAX when possible for add to cart buttons' and also I selected 'always go to the checkout' after a product is added to the cart. So why does the bottom not work?
Thanks
Imma

Hello,

You're actually having errors when you press the "Add to cart" button like : "Too much quantity selected for product Oranges Tarocco Tarocco Oranges - Boxes of 10 kg"

These errors are not displayed because the "HikaShop Cart notification Plugin" plugin isn't published, so you should make sure it's published.

I do not find any "HikaShop Cart notification Plugin" plugin. Why?
Anyway, I fixed the problem in "Legacy settings" parameters. Thanks