He means that, at least for the mobile version, you should create a number of level “chunks” ahead of time and bake lighting for them then randomly choose these level chunks to stream into your game. On PC you can do completely procedural levels, but on mobile you have to make some compromises. Either pre-bake the levels or dumb down the lighting. You might even consider going unlit and/or cel-shaded depending on the art direction and tone of the game.