It sounds like you want to have the data encrypted and shared across the network with users, if this is the case then Symantec Fileshare Encryption will help in your requirement. Which is a different component available with Symantec Encryption Desktop (SED) package.
If above is not the case and you just want the (1TB) drive encrypted then install Symantec Encryption Desktop on windows server which will help to unlock and access the USB drive.
The Symantec Drive encryption feature provides disk encryption and it will need SED package installed on the system to unlock and access this encrypted disk. Please refer below document which provides best practices if you decides to install Symantec Drive Encryption on Windows Servers.
http://www.symantec.com/docs/TECH149613
However I believe fileshare encryption would help in your requirement since the drive will be holding the share folders over network, hence use these file share best practices to test your requirement with this feature.
http://www.symantec.com/docs/TECH176017
Please revert in case of any further queries.
Thanks