I'm trying to download the manual update file of SP3 and I'm getting an error that I can't download the file. Error is :

We're sorry, we are unable to complete the download at this time.

You do not have the appropriate authorization to access this item.

I'm work as an Network Engineer for customers of mine. Some of the customers have locations with a 256k connection. Is there any way I can download the file so that I can update the server manually.