Chinavasion Shipping simply does what it says: returns shipping options and prices for your cart from Chinavasion.
You must have the item's SKU ("Variant SKU" in csv imports) set to *either* the Product ID *or* Model Code from Chinavasion. You must also have the item's Vendor set to *either* "chinavasion" *or* "cv". Any customers' carts which have any items which do not meet these requirements will simply not have any Chinavasion Shipping rates returned, so that you can have accurate rates in stores with multiple vendors.
If you get an error while installing the app, it is probably because your plan does not have "Real-time carrier shipping" (aka Carrier Calculated Shipping) enabled. Contact Shopify to add this.