If you take the partner's first-deposit offer, the published terms are a 600% cash bonus, a minimum deposit of US$20, and a maximum bet of A$5 while a bonus is active. There is also a daily cashback of 10% of losses. Those four figures are the ones that govern the bonus, and they apply on top of the game's own A$0.01 minimum bet.
The cashback is calculated on losses, so a session that ends down is the only kind that produces it; a session that ends up does not. Bonuses and cashback do not change the game's maths, and no bonus turns a high volatility pokie into a low volatility one. Check the full terms on the partner's site before depositing, because the published summary is not the whole document.