Logging into the SAS server at the linux level has nothing to do with SAS at all. It is simply an OS login. You can even start a SAS session on the SAS server without involving metadata.
However if you want to use SAS client tools / interfaces like SAS Enterprise Guide, SAS Management Console and SAS Studio then you have to be set up as a user in SAS metadata.
The SAS Users Group for Administrators (SUGA) is open to all SAS administrators and architects who install, update, manage or maintain a SAS deployment.