Hi,
I would recommend to go in the Joomla plugins manager and configure the settings of the HikaShop cart notification plugin.
There, you can configure how the system should behave after an add to cart. You could for example have it redirect to the checkout (with the cart), or display a popup with a button to proceed to the checkout.
Also, it's possible to display the cart content as a module with the "HikaShop cart module". You can configure it via the Joomla modules manager. If you don't see it after updating, it could be that the template you're using doesn't use the same position names as the previous one and you need to change the position of the module.