It depends how and when you reached this part.
There was "The Door". If you opened it - you likely seen everything and reached "The Safe Button" at the end.
But as seems you never opened the "Not Important Door", you likely never finished the Prologue, else you would open it and seen the real ending.
"The Door" is written in quotes for a purpose, later you see another sign that says smth about "The Door" :) After that Door you have a whole big part of the game.
Anyway, thanks for playing!
P.S. The whole red/orange part with Treasury is a Prologue. After that you have Act 1, Act 2, short Act 3, The End.