It does depend on what state you are in as to what primary school is defined as, in NSW the first year is Kindy, so if your child is in preschool in NSW they are not eligible. If they are in Kindy, yr1, yr2 etc they are eligible.
There is a really simple chart here if you want to check for your state
I don't get the blardy thing, after buying my highschooler a laptop last year thinking that I was!!!