There's no puzzle in Olmstein's Lair. Take your time to learn about things.
You get forward after interacting with the huge porthole.
Unlike normal walkthroughs, in Nice Game Hints you can select just the puzzle you want hints for. Here are listed the puzzles for "Olmstein's Lair" in Gibbous - A Cthulhu Adventure. The guide you choose only contains information about that puzzle, reducing possible spoilers for other puzzles.