download stopped, incomplete error message

Hello interwebz,

I have a new iMac, and am trying to install some old CS4 Design Premium software that I own. There is no CD drive, so I tried downloading the file off Adobe's website.. about 5GB worth. The farthest it's gotten is 3.87 GB, until I receive an error message. Every time. Problem is, it won't show me the full error message. Only: "You do not have permission to acce..."

In System Preferences, it is set to allow apps downloaded from: Anywhere. There is no support for this old of a product. PLEASE HELP!