If you have World Racing Series (I think it works with GP Bikes as well), even the demo you need to:
1. Extract the tracks folder in World Racing Series or GP Bikes program files folder to your desktop (this step may not be required) 2. Get the 'victoria' file and place it in your Kart Racing Pro Tracks folder and... 3. Have fun on the Phillip Island Circuit!
I would reccomend reversing the direction on KRP (turn left out of the pits)