With the two drive encryption products merging, this can get a bit confusing, so I hope this helps:
When you buy a license for Symantec Endpoint Encryption, it also will include a download and license for Symantec Encryption Desktop for Drive Encryption, which would be the preferred product for a standalone installation. After purchase, you can download Symantec Encryption Desktop version 10.3.2 mp4, and install that.
If you have any trouble with the process of downloading/installing, you could open a ticket with Technical Support for assistance.
If you do not receive the appropriate license, you can call customer care at 1-800-721-3934.