Citizenship (Western Samoa) Act 1982
If you are a Sāmoan citizen, you need to prove either that you were in New Zealand on 14 September 1982, or that you entered New Zealand legally after that date, and that you have the right to be here indefinitely – that means that you have a resident permit, a resident visa, a permanent resident visa or Australian citizenship or permanent resident visa.
If you were in New Zealand on that date, you can prove this with a passport, a letter from an employer or school saying you were at work or school that day, or anything else that will prove it.
You don’t need to meet any other requirements.