CS4, CS5 and CS6 are on life support. But they can still be activated providing you have the following:
1. Original media (disks or downloads) you received at purchase and a way to read them.
2. A legitimate serial number for that particular version, language and platform (Win/Mac).
3. An older operating system that can support legacy 32-bit apps.
--------------------------
NOTE 1 : Creative Suite installers won't work on macOS Sierra, High Sierra or Mojave without terminal workarounds.
https://helpx.adobe.com/creative-cloud/kb/install-creative-suite-mac-os-sierra.html
NOTE 2: Creative Suite cannot run on Catalina. Don't even try it. Either downgrade your OS or buy modern, compatible 64-bit software.
NOTE 3: Adobe removed the CS updaters. Your product may not work properly without the updates.
NOTE 4: Legacy Creative Suite is discontinued & unsupported. Use it at your own risk.
=============
Beware of fake Adobe reps who may contact you privately offering to sell you software or take control of your computer. It's a scam, run away!
=============
3 Easy Ways to Identify Genuine Adobe Staff
https://tinyurl.com/10791730