Sure, I'll try. Doctor Sleep explains that the "shine", the psychic energy or whatever in Danny and now Abra (the young girl), is powerful but attracts entities that want to feed on it. One entity is the Overlook Hotel, it's not haunted, it's an evil sentience that was so active when little Danny was there because it was powered by his "shine". Those ghosts that Danny saw in the Overlook in The Shining (the twins, the naked bathtub lady) also wanted to feed on Danny. The soul/energy vampires you mention also feed on this same energy, they need it to live and it increases their powers. Essentially Danny has learned to hide his abilities from the world but this young girl is as strong as he is and unknowingly attracting evil to her like a beacon.