Thank you for adopting her
I have had a few puppy mill dogs that did this too. I think its just habit...they cant do anything else in their cage to get their energy/exercise out. Many zoo animals do the same...its very sad. Most of my mill dogs wont walk on a leash in the beginning either. The circling in my experience slowly gets better. Just keep working with her and she will continue to improve. I started doing puppy preschool with my fosters now when they are from a mill. I have found that has been the most helpful and in many ways their minds are like a brand new puppy because they havent seen or experienced anything outside their jail cell.