The clue is in the message. When you downloaded the SketchUcation toolset you did so as a member of SCF, using your name and your login 'password'. When you first use the SCF toolset you should be prompted to enter that name and password [i.e. exactly matching what you've entered when joining SCF]. Assuming these match, they should then be stored on your computer, and thereafter it's reused so you won't be prompted unless you log-out of its dialog ! You only need to login and password once in the dialog. The dialog is not directly connected to SCF at that point. Assuming you use the same name and password... Thereafter it should no longer prompt you for log-in details...