How does FB/Twitter adult advertising work?

Many people recommend those two, but I wonder how they do it. I attempted it on many ways, just spamming, then waiting and slowly gaining friends on Facebook, but whatever I do, I quickly get asked for ID and phone verification. Free SMS services don't work. So how does it work or are those people speaking about it talking bullshit?

I need to advertise my adult tube site somehow to gain more traffic.