You cant download the App from Australia. Can you just take your Oz Govt International Vax certificate and scan the QR on it when you get there ?
I downloaded it from Australia. I'll try and find where I got it from.
The Oz QR code won't scan into the grune pass app. It's still not compliant. I tried again today and still gets rejected.
I was able to download the GreenCheck app, but it doesn't recognise the Australian QR cert.