If you want camera, which simply follow car without any ability to look around, you should only place Camera Component where you want and uncheck “Use Controller View Rotation” in its parameters. In that case SpringArm is unnecessary.
And you controls blueprint completely wrong, it is only small part, which applies variables to mesh. You missed the whole part, where this variables set and changed. To start with try that tutorial. It is much simpler and better suits your idea. And good luck!