You need to download Symantec Mail Security for Microsoft Exchange (SMSMSE) but cannot find it. You have an entitlement for Protection Suite Enterprise Edition which should give you access to SMSMSE. You do not see SMSMSE as available to download from https://support.broadcom.com/download-center/download-center.html.
The SMSMSE download must be selected via the version number listed for Protection Suite Enterprise Edition.