Your daughter will not have to pay back the hecs-help debt until she starts earning a certain amount. Then it will be taken out of her pay through tax - alternatively she can make additional personal contributions to reduce the debt sooner @Former-Member It took me nearly 15 years to pay mine off but I did have 3 degrees to pay off and sometime in between where my taxable threshold was below the compulsory payment level 
The payments are deducted from pay automatically when someone reaches this threshold (there is a section on new tax forms for employment whereby you include any help-hecs info) so there is nothing further that needs to be done from your daughters end after she has been accepted into the hec-help scheme and filled in that section when she begins employment. The amount being deducted should appear on payslips once it has started.
It is worth noting that once you have paid back the debt contributions do not cease automatically - you need to inform the tax office via a new employment form that your debt has been fully paid - can be a nice little surprise to receive any additional payments via a tax return that year if you have overpaid though 