If you have background in System Administration or any other BI platform administration I would suggest start with the SAS 9.4 or Viya Admin guide. Its a good place to understand the basic architecture and different components that are required to administer a SAS Platform. Then you can add on with respective admin guide for the products installed at your site.
As advised by other you can also enroll in the various training programs that SAS offers.
The SAS Users Group for Administrators (SUGA) is open to all SAS administrators and architects who install, update, manage or maintain a SAS deployment.