If you are new to keeping peafowl, I suggest doing as much research as possible about their care. You can use the search tool on this website for specific questions.
They need clean water and access to food of course, and they do not appreciate being handled or chased more than necessary. The barn would only work if it is completely secure or she will likely escape or end up staying in the rafters. As she is new to your property, she should be penned up right away or she will most definitely wander off. She needs protection from predators including any dogs you may have because even a good farm dog can be tempted by a strange, noisy, and fearful/skittish bird. Even if the dog is friendly, most peafowl will run away if it is around, so it's best to keep them away from each other. I noticed that my peas often cannot get to a roost once it's dark and some can't even find their way inside the coop because the sun goes down so fast in MN. Having lights on during roosting time will help them get where they need to be. The barn sounds like a good place during the time you are quarantining her because they usually prefer to be inside once there is snow on the ground.
Did the person who you are getting her from clip her wings at all? Also, beware of wild birds that may live in the barn because their droppings can spread some diseases.
