I assume you've seen this … https://attend.thepga.com/visit.html

I've been to 5 PGA Championships and the free parking / shuttle service was always very efficient. Expect huge crowds, and lots of lines. Arrive early as possible to get through security and on to the grounds with minimal delay. Bring lots of $$. They will have a massive merchandise tent with all kinds of goodies at all price points. Food and beer are pricey - expect $8-9 beer and $12+ for a hamburger. But it will be worth it, the PGA of America puts on a great tournament with lots to see and do, the course is incredible and you'll see most of the games best players in action.