The error message "There was a permanent error while downloading necessary files. Please try and launch the application again." is typically provided when the system is trying to download an update for TWS but cannot as there is another session running. Please try the following actions:
- Open your computer Task manager and check if there is any instance of TWS.exe or update.exe running and end them. Then restart TWS and try to log in again.
- Restart the computer completely and try to launch TWS again, it should download the update and allow you to sign in after you do that.