This geocache is not located at the posted coordinates. The posted coordinates designate one of the parking lots available in Grey Towers National Historic Site. To get the coordinates, you need to complete the Grey Towers Adventure Lab, in which each stage will give you a portion of the coordinates for the final, which is within walking distance of the five stages. Permission has been granted for the hide by Grey Towers.
The final coordinates are given as
N41 1A.BCD W74 4W.XYZ