if you noticed how every door closes when you get near it, you should know theres weird things on the wall. those are motion detectors. go over or under them.

to get into the bank, use the ladder to the right of the giant bank and enter the garage. inside and to the right will be a large blast door with a ladder behind it. assuming you didnt trigger the motion sensor, climb up the ladder

when you find the managers office, hug the wall to the left until youre under the camera. i dont know how to open the drawer so just remove it and grab the keycard. across from the managers office, you can use the card to get into the underground vault area.

swipe the keycard to open the keypad, the vault code is 5617. youll know you pressed the right button when it doesnt make noise.

press the buttons on the pallet of money on a cart to make it move, follow it and press the unlock button to unlock the garage doors. wait for the truck to come (its very slow but will show up).

you win. this isnt the only way you can do the heist