No certification necessary to skipper a pleasure boat in most states (like Louisiana, where i am), though a few have mandatory boater education requirements, which the Basic Keelboat certif may (?) fulfill. You'll still have to register the boat itself with the state (or if large enough, document it through the USCG). But no license required for you unless you're carrying passengers for hire, which most rec. sailors don't.
Many insurance companies will give you a break on rates if you have a training certificate.
I also recommend as a followup, a Power Squadrons or Coast Guard Auxiliary course. They're more powerboat-oriented, but what they're teaching is piloting and navigation, which is what you'll use to go cruising after you've mastered the basics of sailing. And I think the classes are still free. I took Power Squadron when I was 14 many decades ago, it's still the coastal navigation I use every day (though now much easier with
GPS).