Need Help about API Zoom API Key & Zoom API Secret

I have LMS PHP, my LMS already integrated with zoom, today i bout one host meeting zoom to try it on my LMS,  after that i try to created live class but u receive message it's invalid, I' need help to get Zoom API Key. also i want o know if i have 20 class on my LMS (Virtual School) in this case i will get one API to create classes or what?