You actually don’t need to do any blueprint works for this. The physics system can do it all.
Research UE4 Physics materials. Set the ball and the mat to both emulate physics. Place the mat on a floor and the ball in the air.
Create physics materials for both the ball and the mat (they should be different) and apply the physics material inside the material of each object.
As the physics kick in, gravity will drive the ball down and your physics material (with a restitution of more than 1.0) will bounce the ball back up.