As Sonar 8.5 Producer is a legacy product, it's no longer available for download from the official Cakewalk website. However, you can still find it through third-party sources:

Cakewalk by BandLab can open SONAR 8.5 project files ( .cwp ) natively. Bad News: Some legacy 32-bit plugins from the 8.5 era may not translate perfectly.

The search for a version often leads to a mix of nostalgia and frustration for music producers. Released in 2009 by Cakewalk, SONAR 8.5 Producer remains a legendary digital audio workstation (DAW) known for its stability and professional features like AudioSnap 2.0 and the VX-64 Vocal Strip .

Searching for “sonar 8.5 producer download full” is a digital archaeologist’s quest. While the tool was revolutionary in 2009, the software landscape has changed.

and then apply the 8.5 update. You might find these for sale on secondary markets like legacy Cakewalk Modern Alternatives