Carrier Calculated Shipping must be enabled for your store to access and display Auspost shipping rates at checkout. Our app automatically adds Carrier with name (australiapost_joovii) to the shopify shipping option. Merchant has to add that Carrier to the proper zone to show it in the frontend checkout.
Our app will use the cart object product details to get the weight and use our own dimension management system ( if the merchant already set the dimension of the product in our app) to get the dimension of the product and get the pickup address and deliver address from the cart object and then calculates the rates from mypost api and show it at the checkout.