To get access to the CELS Confluence server in GCE (https://confluence.cels.anl.gov), first make sure you have the Confluence project at https://accounts.cels.anl.gov. Then simply login with your GCE/Argonne account.
Users can create spaces freely on the GCE Confluence site. External users will need a GCE account to get an account on conflunce.cels.anl.gov, however space owners can choose to make spaces readable to external anonymous users.
You will find the latest Confluence documentation at the following link:
Atlassian Confluence Users’ Guide