So excited…just got my NZeTA today. The process was a lot easier than I thought it would be based on what I was reading online. Definitely download the mobile app and apply using it. You only have four steps (scan passport, take photo, pay fee, and answer questions). Although they say it can take 72 hours, it took about 1 min for my approval to come through. Try to complete the process during NZ time regular hours (I did it in the afternoon EST) to minimize possible issues with the app not working. When you scan your passport, you are only scanning the bottom two lines where the letter and number sequence identifiers are— the lines will turn green when you scan it properly— it took a couple tries for me to figure out why it wasn’t scanning. Below are some of the links I found helpful in completing the process:
https://www.immigration.govt.nz/new-zealand-visas/apply-for-a-visa/about-visa/nzeta
https://nzeta.immigration.govt.nz/
The detailed photo requirements really freaked me out until I realized I could take a selfie, just not using the mirror. If you use the mobile app, you have to take the picture using your phone. If you apply online, you can upload a photo.