Adobe CS6 on newer MacOS?

If you buy a new mac which comes preinstalled with macOS Catalina you cannot downgrade the OS to Mojave, High Sierra or Sierra.

You would need to buy a used mac that is capable of installing any OS up to macOS Mojave.

You will also need to determine which of the apps contained in the Adobe CS6 suite will work with the OS your used mac is running.

Use this, https://roaringapps.com/apps to give you an idea if certain parts of the Adobe CS6 suite will work with a newer OS.

I use Adobe Photoshop CS6 on my mac running Sierra, High Sierra and Mojave, and there are certain things that do not work,

very small things that do not matter to me, but you should ask for more information in Adobe forums/ discussion groups.

As you are on a MacPro 2008, the greatest of the silver towers, you should perhaps do some digging elsewhere to find

out how to upgrade the OS from El Capitan.

Photoshop CS6 works for me in macOS 10.6-10.14. I haven't yet updated past Mojave but I guess I must do that in a few years. Photoshop CS6 works OK in light use in Catalina virtualized in VMware Fusion maybe best in old systems like OSX 10.6 server or 10.11 (in 10.14 there are some GUI artifacts because there are no accelerated graphics drivers).

Hello,

Correct.