Lets get a sense of scale. The bar is about 30000 light years long, and contains the central bulge of the galaxy, a roughly spherical mass of stars with a diameter of 10000 ly. It's big.
The supermassive black hole is pretty big for a black hole, but only about 80 light seconds across. Compared to the size of the bar, it is tiny.
The supermassive black hole is found at the centre of the bulge, at the centre of the bar, and entirely within it.
Sometimes a star does fall into the black hole. The black hole is currently inactive, that means that there is not much matter falling in every year. Each year, roughly 1/10000 of the mass of the sun falls into the black hole. This is mostly matter from the solar winds of nearby stars.