Help! What format of the visas do i need to show the officials when I arrive? apps? or paper?

I already applied via phone apps at NZeTA and have been approved.
NZeTA app is very flaky experiencing network problem a lot. I tried 8 times and finally made it through.
I have trying to see how the approved Visa is shown on the app but there is nothing there. It seems the app is only for applying.

I also applied w Australian ETA. The app seems to have a number for my Visa, but there is no email confirmation.
I am worried about relying on the apps for produce the Visa bc if network is not reliable, it would be a very bad day.

It's electronic - when I've applied for AUS visas in the past I've never had to show anything as it's put into the AUS system when approved, then seen by immigration when they looked at my passport.

Assume the same is done for NZ, but as a US citizen, I didn't need one the many times I visited.

Caveat, I haven't visited either in a few years, so quite possible things have changed.

It's possible the airlines might ask the number of your NZeTA. I had printed out the email just in case.

It is not a visa although we think of it as one.

New Zealand citizens with a valid New Zealand passport do not need to apply for a visa before coming to Australia. If you are eligible, we will grant you a Special Category visa (subclass 444) (SCV) when you enter Australia. The SCV is a temporary visa you get in Australia if you are a New Zealand citizen.

There is no indication that the OP is a New Zealand citizen. Everyone else needs an Australian visa.
Nanaland: Make sure you have your Visa approved. Check the immi account you would have been given when you applied.