To set up the Australia Post Shipping Calculations go to Configuration → Shipping → Shipping Providers.
Enable this method, as follows:
In the Australia Post row, click the Edit button.
In the Is active column, check the checkmark.
Click Update. The False option becomes True.
Click Configure beside the Australia Post option in the list. The Configuration window is displayed, as follows:
Enter the information obtained from the Australian Post provider:
Australia Post API Key
Additional Handling Charge