When you get given a GolfLink number after joining Future Golf, it's brand new; this means that there is no golf scoring information about you or your game.
Therefore, when you head over to Golf Australia and attempt look it up, they will show the number as "Invalid".
However, that won't last for long; once you've submitted your handicap cards to get an active handicap, the GolfLink number will become valid and you'll be able to see your scores online via the Golf Australia website.