How to get back into windsurfing?

So I started windsurfing when I was 12, did it for about six years and then adulting happened and kinda fell out of it. I’ve taken the level two course and passed multiple times as a kid but apparently you need a license in california to windsurf(some dude at a rental spot told me I couldn’t rent without a license). How can I go about getting one? Do I need to take private lessons because honestly I know I can just go out on a lake and crush it. I was offered a written test to prove I knew what I was doing but without any chance to refresh myself I failed by a few points.

Any help would be awesome!