Hi,
I can't check your website:
take.ms/DDJjJ
Normally a Joomla component will pickup the proper Itemid from the menu link
You're right. That's what HikaShop does by default when you don't select any menu in the menu option of your module and don't set a canonical URL in your category/product.
In that case, the system will search for a category listing menu item and use its id automatically as Itemid for the links.
And so you don't get a 403 error in that case.
As I explained in my previous message, if you get a 403 error, it's either that you selected a wrong menu item in the menu setting of your module, or that you entered a wrong canonical URL in your category/product.