WPMU DEV login on Wordpress

I'm trying to log in locally to the Dashboard but keep getting this error message in login.

This domain has previously been registered with WPMU DEV by the user Sue(s*e@s*b*st*dios.com). To use the dashboard plugin on this domain, you can either login with the original account (and upgrade it if necessary), or upgrade your trial to a full WPMU DEV membership.

I'm using a Mac and hosting on MAMP. How can I work around that? Thanks.