You can find guidance here: https://www.employment.govt.nz/leave-and-holidays/other-types-of-leave/coronavirus-workplace/leave-and-pay-entitlements-during-covid-19/
Look for the table about 1/3rd the way down and the section: Employee is not at the workplace, cannot work from home, and is not sick.
Note the * by Leave Without Pay.
* If the employer is receiving a subsidy from the Wage Subsidy Scheme or the COVID-19 Leave Support Scheme, all named employees must receive a minimum payment depending on their circumstances.

So the short of it is:

• Ensure the work place is safe
• If the employee is on the Wage Subsidy
  • Pay at least that
  • Move them to Leave Support Scheme
• Otherwise either:
  • Apply for the Leave Support Scheme for the employee
  • Employee uses leave
  • As a last resort, work though a disciplinary process