In the states athletes get to choose their classes first and can be given a bit of leeway for assignments during their seasons. Is this the case in NZ?
Once you’re an U23 level you can receive The Prime Ministers Scholarship. This pays for your course fees and also offers you a 5k study grant. Pretty helpful provided you pass all your papers and maintain your sporting commitments!
I can only speak for rowing ! In my experience I’ve been given extensions and permission to sit exams outside off campus. The uni isn’t aligned with the sporting programme so you just need to be organised enough to let your lectures know when you have sporting commitments coming up!