This is a Measure & Make pattern, which means you can make it for any age, in any yarn of your choice.
However, do not use any yarn thicker than fingering. The sweater will be too thick and too heavy, and you will use a lot of yarn. With fingering, you will need between 500 and 900g depending on the size you are making.
Choose a hook suitable to the yarn you are going to use. Swatch and make sure your tension is not too loose.