Go to the nearby room during the next day. Then enter the room in which previously you had to activate the camera. Hide in the closet shown on the picture and wait.
While in the closet you will see Trinity trying to enter the closed room. Employee will appear and interrupt her. The woman will enter the nearby room for a moment and the employee will enter the code to close the door. Notice the Trinity mask appearing in the upper left corner of the screen.
Press space and you will learn the code. You don't need to enter it manually. From now the door secured with this code will open whenever you interact with them.
Leave the closet at right time and press F1 to start the day from the beginning.