It's deff not via the license plate screws. That's what you do if you want to get it to connect the ghetto way The rest of the answer I do not haz.
Once you get the 4 tabs/grommets off from inside the hatch lid, you can pull it out so the tab surface is beyond the lid. Then slide it down. There is a lip on the bottom of the plastic frame. If you pull it straight off, you'll likely break off the tab/gutter. Mine had double sided tape on it. So took abit of effort to get it off. Not sure if they came that way from the factory.
Chances are the plastic tabs on the backside are broken. They almost all break. It was yet another brilliant and cheap design by VW. There is one that is behind the wing motor and its not easy to reach.