Jyn’s motivation changes throughout the film. She goes from trying to erase her past mistakes, on to finding Saw Gerrera and learning about her father, then to fixing her father’s mistakes. That was her motivation.
She didn’t want to be the daughter of the man who created the death star. She wanted to be the proud daughter who brought down her father’s death star at his request.
The reason for the Vader hallway scene was to show the audience just how evil this villain is, and why the heroes are fighting back against this tyrant throughout the original trilogy.