If you have a Differ account and want to login for the first time, then send an email to the helpdesk at Differ and ask to have your account added to the gitlab-users group. Once you have been added you can login under the DIFFER tab using the SURFconext button and choose Differ. If you are an external person, then please create an eduID account first (https://eduid.nl), after that has been done, use the SURFconext button and choose eduID to login.