Preheat oven to 350°F Make the filling: Add fruit, maple syrup, arrowroot, lemon juice, and lemon zest. Bring to a boil, while smashing & stirring with a wooden spoon. Cook until the mixture is thickened. Chill in the fridge until ready to use.
Press a little more than half of the crust mixture into prepared pan. Bake for 12 minutes. Remove from oven & allow to cool for 5 minutes.
Spread fruit mixture evenly over crust. Sprinkle remaining crumb mixture over berry layer.