If you're getting an invalid Username/Password error when launching SIMS, it's possible that you may not yet be granted access to SIMS (if you're a new or returning staff member), or they may be an issue with your SIMS account.
You do not need to log in/you will not have a manual login for SIMS - you'll need to speak to the MIS department so that this can be investigated for you. You can find them either the back at reception, or can contact them via the Mojo Helpdesk currently (although they will soon be transitioned to this system.)
If you had an incompatible database issue and then tried to log in and got this error, please see this article for more information on how to resolve your issue.