The ladder appears on a small locker in one of the rooms, you have to find this ladder (inside the locker) pick it up anad take it to the vent wich spawns on a wall (usually it glows red so you can find it more easilly by looking for that) then you escape and gain money to buy stuff, i reccomend you get one of the anomaly scanners because it's hard to find those things at first when you're starting
To get to the fun part buy a spray and throw it to the monster, you may need one of the membership upgrades first to get more options, sadly it's still a WIP so there is no much content to go around besides three scenes