I see you have not had an answer. I can answer based on my knowledge of what can happen after death. I can’t say if that scriptural quote is accurate, but there is “total darkness” and I can indeed see it being described as “outer darkness”.
If you are extremely wicked, really really as bad as it gets, the very worst position in the “hells” is in a personal darkness. It is as if a wall surrounds the person, and they can perceive nothing at all. They are totally alone with their thoughts. They know they are “alive” but its just that – total darkness. How long it lasts I have no idea, but based on spiritual laws it will last until some change occurs in the thought processes of that individual. In other words a start is made on taking responsibility for the evil they did, and their also beginning to reach out in the hope that things can change. But people are remarkably stubborn and resistant to change, so these things do not happen fast.
You may see from this that I am sharing hell is not permanent, and it is not a place of fire and brimstone. There is no place in our universe where the Law of progress does not act. So change occurs. It can be temporarily held up, but change will occur. Where do you learn these things? Well from those frequently dreaded “dead guys” speaking through mediums. And yes that too is not of the devil, who does not exist anyway.