Thanks for reaching out!
If its the certificate farthest from the door, you'd have to choose the other option in the choice before the final boss.
Depending on the choice, you'll get a different boss and certificate
Hope that helps!
It honestly brought up more questions haha, but no worries! Knowing everything that I know, nothing stands out to me as "final boss". I have all the wrong turns.
Though, I'm wondering if I haven't even beaten the final boss yet. Would I have had to defeat the final boss in order to have every other certificate except for that furthest one?
(And please dear lord almighty don't tell me it has something to do with destroying ALL the cameras because theres one in the bathroom that is just mocking me because I can't get to it. If it does, then I have to ask for a hint to getting that. Again, I'm sorry for asking! I've just never been good with puzzles and I'm genuinely at a loss here.)