AC smells horrible - Clorox in the drain tube fixes it temp
The  condensate drain line at your unit should have a trap built into it to keep sewer gasses from being pulled up that line. Opening a window may worsen the problem. Since you live in an apartment, I would have a licensed HVAC company do the work. You could then contact the apartment manager for a refund. You could also contact the housing authority for advice on how to rectify the problem. Other solutions may be justified such as a small condensate pump to handle the condensate from your unit only. If you are handy, they cost around $40.00 dollars from "amazon ", or just have the previously mentioned professional do the work.