It's because it's early in development. There's no doubt the missions aren't that intuitive yet. In fact, we already have plans for a better mission system that may be more visual.
Until then if you still wish to know, I can tell you the vents should go inside a room on the floor, with pipes under it going to an oxygen generator.
You can also see an example of how it's laid out if you access the DevStation from the menu, which also contains everything else that's currently available in the game.