macOS Catalina (macOS 10.15) requires apps to be 64-bit. That means older 32-bit apps will no longer run.
- InDesign CS6 is 32-bit so it will not work on macOS Catalina.
- Illustrator CS6 is 64-bit, but I’ve read that it has 32-bit dependencies so I’m not sure if it work on macOS Catalina (I have not tested it myself).
- Photoshop CS6 is 64-bit and should work on macOS Catalina.
Adobe’s Creative Suite was retired years ago and is not supported. If you want to continue using Adobe’s creative apps (InDesign, Illustrator, Photoshop, etc.) you must join the Creative Cloud or remain on an older version of macOS (Mojave or prior).