No, you don't need to open a new account. Please login to IB's account management site at https://www.interactivebrokers.com/sso/Login . Click on "Manage Account" from the menu at the top, then choose "Add Accounts", "Link Account to Advisor/Broker" from the sub-menus.
If the "Link Account to Advisor/Broker" menu item is not there, please contact IB to ask why you cannot link your account to an advisor/broker. This seems to happen when an account has been "linked" to create a second IB account. If that is the case for your account, your best bet is probably to open another account with IB using this link (which will create a new account, already associated with Global AutoTrading and ready for autotrading).
The diagram below shows how to link an existing IB account to Global AutoTrading. Please Contact us (please specify your IB account number in the comments box) and Global AutoTrading will provide you with the information necessary to link your account.