That message usually pops up when you are standing in a members only area (i.e - Catherby, Yanille, Relleka etc.) and are trying to log into a non members (free) world.
You will have to move to a free area to log into a free world. Make sure you are actually logging into a members world.
If you are still experiencing issues, you may want to make a thread in the Community Led -Tech Support forum.
- Seeing as the suggested topic is involved in conspiracy theoriess, politics and otherwise hate speech/harrassment, the RuneScape forums is not the ideal place to discuss such a topic.