Congratulations on your decision to adopt a new Macaw!
Have you spent some time with this bird? What is her temperament? I presume she is able to be handled and that you have personally handled her. If you've already become acquainted with her to some degree, that should provide you some assurance on how you and she may get along together once she arrives home with you.
Some Military Macaws can be a challenge. I'll tell you that mine, Maynard, who is a wild caught bird and whom I've had for over 30 years, certainly is challenging at times. But individual birds of most any species can turn out to be a challenge, whereas others can be wonderfully adaptive, easy-going and affectionate friends and family members. I've encountered Military Macaws just like that in fact. Hopefully yours will be one of those.
I'm sure others here may have some further advice for you. I wish you well with your soon-to-be new flock member.