I'm sure you are correct about not being able to activate a trial version, but the download link you gave me includes the following text:
When it is time for you to purchase Symantec Protection Suite Enterprise Edition for your organization, there are a number of ways that Symantec can help you with your purchase.
Here are the purchase options open to you:
I had assumed that the last option meant that the trialware could be activated as the full version with a valid license.
Incidentally, the download link you provided gives me the same error message when I try to download:
Sorry! Your request could not be processed. Please try after some time.