By default, client accounts do not have Trading Access and cannot sign into TWS or WebTrader. They are limited to Advisor Portal where they can view Statements and Trade Confirmations, as well as perform account administration tasks. However, there are occasionally requests by advisors that a client be given the ability to trade their own account.
Information:
There is a feature that allows the Advisor to give Trading Access to his Clients. This can be enabled by the Advisor in Advisor Portal in the Manage Clients section followed by Trading and Configuration. The Client would then need to subscribe to market data if they desire and would be able to trade only his/her own account.
Working orders would be accessible by either the client or the advisor.