We fly from Amsterdam to auckland but we have a stop at Beijing Capital Airport.

It is an international to domestic transfer at PEK in T2. You don't need to apply for a visa if your stop over is within 72 hours. However, you need to collect the luggage and recheck them. Hereunder is the correct procedures:
Flight Arrival - Inspection & Quarantine, Exit and Entry Frontier Inspection - Customs Inspection - Baggage Claim - Going through Transfer Formalities - Waiting & Boarding