How to use the keycard

How to use the keycard? I can’t understand how to use it. I don’t like the new system, someone answer me as I’m ragequitting soon with this keycard

As inmate, or as cop? As a cop, the keycard literally does nothing, because you already can open doors. However, if you’re on the inmate or criminal team, you can open doors with your keycard, while it’s equipped in your hand.

Other person is wrong. The way you do it is match the numbers. The first top number may be 9, so when the lower number on the bottom of thenpopup gets to nine, press it. The second number could be 7, so you try to match the numbers basically. Once you get the hang of it it is easy.