The scariest thing about MAP is looking at scores and wondering just what it means when your seven year old scores higher than fifty percent of eleventh graders.
I think the biggest thing is to soften the landing for a kid with perfectionist tendencies as the test is geared to present harder material and a kid should expect to miss half the questions presented.
If the school shares the full results they cover levels in a wide range of sub topics and you can get a sense of gaps and strengths in a topic that way. If she hasn't used quizzes on a computer before, you might try some website to get her comfortable with the format.