No—a ring flash is not an absolute requirement for macro photography. It’s mainly useful if you specifically want the even, shadow-minimizing look that ring lighting gives.

For macro, the main challenge is getting light into a very small area at close distance, especially when stopping down for more depth of field. A regular on-camera flash can be blocked by the lens when you’re close, which is why ring flashes are popular—but you can solve that more cheaply by moving a normal flash off-camera with an off-shoe cord or wireless trigger.

Other options can also work well: a small softbox, a ring-style reflector for a standard flash, continuous lights, or even DIY lighting placed close to the subject. Macro subjects are small, so you usually need light placed well rather than lots of power.

So: buy a ring flash only if you want its specific lighting effect or convenience. If you just need more illumination, off-camera flash or simple continuous lighting is often enough.