The Symantec Enterprise Agent (SEA) used to be available for download from the Cloud SWG (WSS) Portal, but it is now available for download only from the Symantec Endpoint Protection (SEP) portal.
Cloud SWG
To access the download, you should have the SEP product, and you can find the download in this portal. See the snippet below, as reference. It's no longer a part of the Cloud SWG (WSS) Portal. See the snippet below for requisite guidance.