I think it's actually called a 3.1 metre, the "bag" is a bit longer than the actual canopy. Having looked at a picture of a 524, you might even get a 3.6 on it, but I would not go that big without measuring first.If the 524 is the one with the side dinette and full rear washroom, then a 3metre one should fit rear to just behind side lounge window.
Our Emerald was similar layout, we had a 2.55m on it and there looked to be room for a 3metre.