There is no indication by LE that she knew her abductor, or that she alone was targeted. In fact, the opposite is true.
The urgency with which the FBI classified her missing person's case as a kidnapping, the way they put billboards up all over the Midwest, the fact that they mentioned they were still in the process of speaking with all of the owners of that kind of car, and the fact that they said they were looking for a white male who had approached other women, all indicate that she was selected at random, a chance occurrence of a bad person crossing her path while she was standing on the side of the road.