First, you have to take the B1 (Zumba Basic Level 1) workshop. Have you done that?
At the B1 workshop, you’ll have two options. You can join ZIN at your workshop and get extra free materials at your B1 workshop. If you don’t want to join ZIN right then, you have up to one year to join. At that time, you must either re-take B1 or join ZIN in order to maintain your license with Zumba and the rights to use the Zumba name.
ZIN have more licensing rights than Zumba instructors who choose not to join ZIN.