Joey, of course, can go right in. If you want to get Rosa in, that'll take a little more work.
The office door has a keypad at the door, so you'll need to know his code before Rosa can get in --
-- and you'll find that code at Emil's apartment.
How do I find Emil?
What should I say to Emil?
The code is Kendra's birthday, which you'll see on a photo of Kendra, Emil, and Lia in Emil's apartment; it's 1029. (But this won't work until you've been to his apartment and seen it for yourself.)