Help to fix a small issue in WooCommerce site.

I have followed the following tutorial provided by the divi theme support for being able to add the quantity field in shop pages at woocommerce. https://aceplugins.com/how-to-add-a-quantity-field-to-shop-pages-in-woocommerce/ But I have an issue and I would like to have help to fix it.

For example, if I add 3 items for one product... it does not update automatically the items at the cart at top right corner... and if I select 3 items for one product, it does not sum up 3 to the total, it just sum up one...

The website is mysalonsecret.com