Hi stev379,
Let me answer this step by step.
You are currently using Symantec Endpoint Encryption server: 3.3.0 (Build 8471) and clients are on 10.3.0.8471, looking to upgrade just one client to the latest version i.e 10.3.2 MP7.
PGP Client only upgrade:
This is a local client upgrade and can be done using the SymantecEncryptionDesktopWin64-10.3.2MP6.exe that you have downloaded on the client machine. Also this should not impact the client and server communication, even If it does, then you can change it back. Just take a note of it before the upgrade, and read through this article:
http://www.symantec.com/docs/TECH149792
PGP Server Upgrade:
The upgrade for PGP server is always a PUP upgrade. Once the server is updated to the latest version, the package created will be the updated package.
EXE/MSI are for client updates packages, not to be uploaded on the Server.
Different Products under the same serial number:
From Encryption, Symantec has 2 differnt product offerings under the same license agreement.
Symantec Encryption Management Server (Previously known as PGP server) and the latest version is 3.3.2 MP7/10.3.2 MP7. This is one that you are using.
Symantec Endpoint Encryption 11.0 is the other product that is available under the same license and serial number,
Symantec_Endpoint_Encryption_11.0.0MP2_EN.zip that you have downloaded has the instalation files for it and has nothing to do with your current setup.