When do I start seeing pmcs? [new player]

i’m pretty new to this game and have only really seen youtube videos so I don’t really know what im doing most of the time. That being said, i’ve been running ground zero and have done so at least once or twice the past couple days and I’ve killed and been killed but every time i check the report it’s always a scav. Is there just something i’m not understanding like a system that puts new players with bots or something or have i just been lucky?