You can read up on it in this thread. Basically, there's no offsite linking at all. They also had a requirement to be exclusive to Rendo. I can't find that clause anymore. Maybe I was mistaken. But still, people tend to offer free stuff to promote their own work. If you can't do that, then what's the point. For me, it was more about the principle of it. When they start boxing you in, it's time to leave. I personally feel great now that I've move to another site and I've actually started doing more free stuff.

https://www.renderosity.com/mod/forumpro/?thread_id=2897445