It works like this: when you submit your application for an Australian university program, you need to do so via the state-specific admissions centre (refer to this article for more information).
When your results are released (e.g. mid-January for CIE), you will need to submit them to the admissions center so that they can process it and give you an ATAR score. The ATAR score derived from your CIE results will not only be based on your results but is also influenced by everyone else who has applied for admissions. The exact method for calculating these scores is usually undisclosed, but we do know that it’s based on the raw marks achieved by all applicants.
(Side note: there are a lot of online calculators that seem to produce accurate conversions, but since it may vary from year to year based on the results of the people who apply in that year, there isn’t really a consistent or straightforward way to convert students’ results from NZ marks to ATAR.)
After that, universities will use applicants’ results to make interview offers or course offers.
Before we wrap up this question, here’s a final bit of advice to improve your chances of getting in:
First, your focus should be to do your best at school so that you have a better chance of ranking highly. We’ve seen NZ students gain entry into Monash University and the University of Adelaide with 2 A*s and 2 As, as well as other students with slightly higher and lower results who also made it into other medical schools in New South Wales, Queensland, and Western Australia.