Got this email this morning. Says you can earn credit by using the Amazon Assistant on your desktop browser
Open Amazon Assistant for 5 days to unlock a $5 credit. For a limited time, you can earn a $5 credit for opening Amazon Assistant on desktop for 5 days. To get started, click on the Amazon icon in your desktop browser and activate challenge by May 22nd - you'll have two weeks to earn your credit! See below for terms and conditions.
I downloaded it but Amazon assistant doesn't have a setting for Amazon AU - are you sure this is an amazon AU deal?