No, you don't need to create a new event campaign if your school has signed up through Australian Fundraising.
The booklets and instructions provided by Australian Fundraising to participants will direct them to myprofilepage.com.au or plantadifference.com.au from where they can create a fundraising page.
This is all automatically linked to GoFundraise to process online payments. There is no need to create a new event campaign specific to your school's event.