Elsewhere on their website, and explicitly on the Visitor Visa information page when reporting particular citizenships or residencies, Immigration NZ provides a list of types of satisfactory evidence, which "can include"
proof of accommodation pre-payment, like hotel pre-paid vouchers or receipts
credit card statements
a 'Sponsorship Form for Temporary Entry' completed by an acceptable sponsor.
The page continues to describe evidence a sponsor can give, which varies to include
It should be noted that cash is a reasonable evidence of funds, but for security reasons, carrying such amounts is discouraged.
In effect, you need to show that you can cover costs to the amount required without much delay by either having the funds immediately to hand or, in the case of your accommodation, having already paid for it.
These requirements are stated per person, so if you are planning for a group, you must multiply the amount stated by the length of your trip measured in months by the number of people going on the trip.