Hello,
It is not supported installing Backup exec for windows software on a 64 bit Platform.
Kindly refer the Software Compatibility List (SCL) for the same:
Symantec Backup Exec 10d (10.1) for Windows Servers - Software Compatibility List (SCL)
http://support.veritas.com/docs/278254
Whereas you can install Remote agent on 64 bit Server.
10d (10.1.5629) Hotfix 1 - Extended 64-bit (x64) Remote Agent for Windows Servers (RAWS) (Adds support for remote computers running 64-bit extended chipset Windows operating systems)
http://seer.support.veritas.com/docs/280701.htm
How to install and uninstall the 64-bit remote agent for Windows servers to remote Windows computers using the command line
http://seer.support.veritas.com/docs/275657
Thank You,
Shweta