Doodly rainbow is a paid add-on. It is not included in the purchase of either the Standard or Enterprise license by default. You can also learn more about it here: https://www.doodly.com/rainbow/
TUTORIAL
Doodly: What is Doodly Rainbow?
Learn what Doodly Rainbow is — a paid add-on that enables color animation in your Doodly videos. It is not included in the Standard or Enterprise license and must be purchased separately.