Yes, you definitely can. In fact, that 'flaked coconut' could very well be dessicated--'flaked' refers to the shape of the product while 'dessicated' describes the type of coconut product it is. It's much like comparing 'mini chocolate chips' to 'bittersweet chocolate'--one is a measurement of size and shape, and one is a type of chocolate product.
While you can definitely use either one, there are two considerations for baking that might lead you to adjust the recipe a little bit.
- If the 'flaked coconut' is fresh or 'dried' rather than 'dessicated' (that is, very thoroughly dried), consider removing a small amount of moisture from the recipe, like water or milk. If the recipe calls for 1c of milk, for example, you might consider using a 'scant' cup, or just a bit under a cup.
- If the recipe specifies sweetened coconut, and you're substituting in unsweetened coconut (or vice-versa), you'll need to compensate for that by adding or removing a few tablespoons of sugar per cup.
One last caveat: for macaroons, I suggest using shredded or grated coconut rather than flaked. Larger 'flaked' pieces would be difficult to work with and shape, and would have a much bigger effect on the texture of that dense, coconut-packed cookie than they would in a recipe where they're incorporated with other things.