New Zealand requires a student visa for study longer than three months, applied for online after you hold an offer of place from an approved provider. The documentary requirements are conventional: offer, funds, accommodation arrangements, health and character evidence.
What is not conventional is how explicitly genuineness is assessed. New Zealand decision-makers consider whether you are a genuine student intending to study, and a refusal on that basis does not require any document to be missing.
What genuineness means in practice
It means your course follows logically from your academic history, your funding is proportionate and explained, your ties and intentions are coherent, and your account of why New Zealand specifically holds together. A student moving from an unrelated field into a lower-level qualification will be asked why, and the answer needs to be real.
This is preparable. It is not a personality test, it is an argument, and the argument should be visible in the documents rather than only in a statement.
Funds and health
You will need evidence of tuition and living costs for the first year, and a plan for subsequent years of a longer programme. Medical and chest x-ray requirements apply for longer stays and must be completed with an approved panel physician.
Insurance meeting the required standard is mandatory for the duration of the visa.
Work and afterwards
Limited work rights attach to most student visas, and post-study work rights depend on the level and location of your qualification. Those rules have changed more than once in recent years and are worth verifying against the current position rather than an older summary.
Choosing a qualification level without checking its post-study consequence is a common and expensive error in this corridor.