Where is the red card?

Hint 1 of 4:

The red card is needed to open the door that you should've seen when you
swiped the blue card earlier on.

Hint 2 of 4:

Check the KTIT building.

Hint 3 of 4:

Look in the security room (across from the broadcasting room).

Hint 4 of 4:

Check around for a secret passage in the security room.