If the WooCommerce plugin is being installed, the Menu module can display the cart quantity count.
Enable the Cart Quantity option
Open the Menu module setting
Open the Elements options group
Enable the Show Shopping Cart icon option
Enable the Show Cart Quantity option
Pro Tip:
The color of the Cart icon can be changed from Design Tab > Icons > Shopping Cart Icon Color.
The text color of the quantity count can be changed from Design Tab > Cart Quantity Text.