Has anyone here had any experience with Australia and NSW Covid tracer apps?

I am going to Sydney for a couple of days and found there are two "tracer" apps (on Android):

Service NSW – Apps on Google Play

COVIDSafe – Apps on Google Play

Service NSW seems to scan COVIDSafe QR codes so it seems I can use this one. The COVIDSafe on the other hand seems to be an Australian initiative and uses Bluetooth. I tried to register but it says my phone number has already reached the limit of registrations - on my first attempt. I suspect it just doesn't like my six-digit New Zealand mobile number but instead of giving an error message it just spits out something else.

Can I just use Service NSW?