You will receive an error message at the point of installing ESET Endpoint Encryption if you have selected the wrong version for your operating system. If you are unsure of which bit operating system you are running, please see this knowledge base article: KB107 - Should I download a 32-bit or 64-bit version of ESET Endpoint Encryption?

There are two different versions of ESET Endpoint Encryption (EEE), a 32 bit and a 64 bit. The version which you install must correspond to the operating system you are using. 

If you are trying to install the 32bit version of EEE on your 64bit operating system the message "Error: This installation does not support EEE under 64bit Windows."

If however you are installing a 64bit version of EEE on a 32bit operating system, you will see the message "This installation package is not supported by this process type.  Contact your product vendor."