There are two distinct things: an operator ID and a flyer ID. The first is basically just a register of ownership. No test or competency, unlike the latter, which does require you to show you know a little about the rules.

For sub 250g drones without a camera, you don’t need either of these. If it does have a camera, you need an operator ID but not a flyer ID. So you have to fill out a form with your name and address, and stick the ID to your drone, but there’s no certification element like there is when you have a heavier drone and need a flyer ID too.

Registration is required for <250g drones if they are camera equipped, but not if they are toys.