For pinball you need 2d physics. So make blueprint with ball hovering about 10 units above ground. To do ss create scene root, ball that is above 0 and physics constraint that connects ball and root.
For physics constraint let it be free in x and y and locked on z and all rotation axes. Enable physics for ball mesh and override mass and set to something you like. There you got your physics ball.
Now build some shallow box so it can bounce and you can test. In ball blueprint add event and add impulse (mark velocity change), give your ball kick when event is called.
Last thins is physics material. Create 2 of those add one to box material add another to ball material. Set it values to bounce more or less, friction etc.
Also experiment with collision of ball. I think simple sphere would be best for it, but i am unsure i never needed such precise physics collision. For me enough is if my asteroid bounces a bit and spins.