Any website offering a DMG file labeled "Adobe Illustrator CS6 Portable Free Download Mac" is lying. At best, you are downloading a stolen, cracked installer (which is not portable). At worst, you are downloading malware.
Adobe Illustrator is proprietary software. Downloading a "portable" or "cracked" version is software piracy. This violates Adobe’s End User License Agreement (EULA) and international copyright laws. While the likelihood of an individual being sued is low, the risk exists, and it is a violation of professional ethics for working designers. Adobe Illustrator Cs6 Portable Free Download Mac