He needs time with a sports psychologist more than he needs time in the gym.
^^^This^^^
Something has gotten into his head when it comes to the games. He's not the first guy to struggle with outside shooting and he sure as heck isn't the only guy who struggles with free throws. But most of those guys don't let it stop them from shooting.
When a guy has so little confidence that he passes out of a dunk attempt because he might get fouled and have to shoot free throws...that isn't going to get fixed by just "seeing some shots go in" to restore confidence.
It's like his confidence is so far gone it has to be completely rebuilt.