If I fail the exam, can Immigration New Zealand still grant me a visa?

The Immigration Bureau is not interested in grades. As long as the school admits you, it will give you a visa.

You can continue as long as the school allows you to continue studying.

A visa (visa) is an endorsement or stamp by a country’s sovereign authority on the passport or other travel documents held by its own or foreign citizens to indicate that they are allowed to enter or exit the country’s territory or pass through the country’s territory. It can also be said to be an endorsement-style certificate issued to them. In summary, a visa is a document issued by a country's entry-exit management agency (such as the Immigration Bureau or its embassy or consulate abroad) to express approval for entry to foreign citizens.