For the App to show live Auspost rates in your checkout , you need to have Carrier Calculated Shipping enabled.
Carrier Calculated Shipping must be enabled for your store to access and display shipping rates.
To be eligible, your Shopify plan must meet both of the following requirements:
1. It is on the Shopify plan or higher. (Not Basic Plan)
2. Your Shopify plan is changed to paid annually.
Once both of the above is true, please contact Shopify support who will enable it immediately when requested.