You will need a cage no matter what size bird you get, from the largest to the smallest, It will also need to be large enough for the bird to have room to stretch his wings, climb around and have toys in there. You MUST NOT just have a perch for many reasons. There are many dangers in our homes, no matter how safe we think we have made them. A bird will chew anything if you give them the chance to.
A cage is the MOST important item you NEED to buy BEFORE getting a bird.
Also a macaw (or any other bird) sitting about in a room all day is soon gonna get bored