Ann: Intention to transition to an Active ETF, page-9

There will be a market maker, a third party who can create unit to sell or buy units which they'll sell back to the manager.
The prices they buy or sell are based are slightly lower/higher than NTA.

Its the market maker that ensures it trades close to NTA.
In a fund I've owned from time to time (MKAX), I notice the market maker dissapears for short periods in real high volatility. MHH will be big thou so that may not happen.