Patients are automatically connected to the A* navigator if you have any A* objects in the model. You need to connect staff members to A* too if you want them to respect A* objects. You can do this by double clicking the A* Navigator object in the model and then in the Members box hitting the green plus button, then choose Staff and hit Select. All your staff members should now have a purple circle under them indicating that they are connected to the A* navigator. You can also add locations to the navigator if you want people to not walk through them.

You add Locations and Props in the same way. You can even select them all at the same time after pressing the green plus button:
