The current setup of the simulator gives $50k cash with $200k buying power for stocks and options. If for any reason you have more than $200k worth of stocks or options in your open orders and/or in your current positions, you will receive this error.
To rectify this issue, close out all your unfilled open orders in your open orders window or pressing the hotkey CTRL+Q to cancel all open orders. Then exit old losing positions as well, as it is a good habit to cut your losses quickly.
If you still need more buying power after following these suggestions, simply email us at firstname.lastname@example.org or send us a message through our support portal, and we can update your margin and buying power to a higher amount.
Still have questions? Please reach out to our Support Team, and we'd be happy to help.