Directly downloading Adobe Premiere Pro CS6 for Mac OS X is no longer possible through official Adobe channels as they have discontinued all public downloads and support for Creative Suite 6.
Adobe’s current model is subscription-based (Creative Cloud). For Mac OS, the recommended path is: adobe premiere pro cs6 mac os x download
Even with a legal download, you may encounter errors because Adobe’s CS6 activation servers are still running but can be finicky. Directly downloading Adobe Premiere Pro CS6 for Mac