1. Check this KB -
Symantec Endpoint Protection client installation fails due to lack of permissions on Windows Vista or Windows 7
http://www.symantec.com/business/support/index?page=content&id=TECH96238&actp=search&viewlocale=en_US&searchid=1304623301758
2. Log into the licensing Portal to get your product license.
https://licensing.symantec.com/acctmgmt/index.jsp?sessiontimeout=yes&localeStr=en_US
If that does not work for you, you can contact the licensing department at 1-800-721-3934 and select option
3. Double-check your Server name, user name, and password