Place the door flat across two sawhorses with the hinge cutouts facing up. Place one side of a hinge into each one of the hinge cutouts. They will only fit one way. The beveled sides of the screw holes should be facing out. If they fit tight, use a hammer to tap the hinge so that it fits flush into the side of the door.
Insert one screw into each hole. Using a cordless screw gun, tighten the screws as tight as possible on each hinge.
Place a 1/2-inch shim on the floor beside the leg of the frame that has the hinge cutouts on it. Stand the door up vertically at a 90-degree angle to the frame. The edge of the door should be resting on the shim. Place another 1/2-inch shim on the outside edge of the door.
Swing the hinges out flat. As you are holding the door vertically, shift the door to the left or right as you manipulate the loose side of the hinge into the hinge cutouts on the frame. When you get one to fit, use a hammer to tap on it so that it flushes into the frame. Repeat fitting the other three hinges into their respective cutouts and tap them in.
Place screws in all the holes. Use a cordless screw gun to tighten all the screws securely. Remove the shims.