You went along the alley until you came to a gate, with a voice print lock. You (I assume) found a voice recorder, went back to one of the hyenas, and got a clip of him talking. So now that you've got that recording, the next logical step would be to take it back to the lock and try again.
You are correct though, the guide focuses just on the scene collection, as walking through the entire game would make it pretty massive.