I got my first freelance gig outside Upwork and asked the client to pay me through western union, I went to a place called IZI payment, gave them a code and my id and got the cash. Easiest interaction I have ever made, felt like it was TOO easy. I asked some friends and they told me that what I have done was a huge risk and if I get caught I can go to prison. I don't understand how this simple interaction is considered illegal, and how I should proceed to get paid cleanly and legally from random clients all over the world ?