Almond flour and almond meal are not the same thing. Almond flour is made from blanched and finely ground almonds. Almond meal is ground almonds. Almond flour works best in this recipe.
The lemon oil adds a nice flavor to the sugar cookie. It is available at most kitchen or cookware stores.
Nonstick baking mats are silicone baking surfaces. They are available at most cooking stores. Since they are woven with glass, only use plastic cookie cutters or a plastic knife.