CS3 - New Install

[cgauts13]

I contacted Adobe, they gave me step by step to install my CS3 on my iMac Mojave. I believed to have followed every step. However, when I downloaded their install of CS3 onto my Mac, it seems to be giving me trouble. I clicked on SETUP, but it gives me a message of "Setup" is an app downloaded from the internet. Are you sure you want to open it?" I say OPEN, bounces then disappears. I turned off firewall. I am not sure what I am missing? Please HELP!

[John T Smith]

Apple did not maintain backward compatibility, so try this to install old programs
https://helpx.adobe.com/creative-cloud/kb/install-creative-suite-mac-os-sierra.html

For anyone else, also read to the end of

https://community.adobe.com/t5/Get-Started/How-to-reactivate-old-CS3-software-on-a-new-machine/td-p/...

[cgauts13]

This is good! Thank you, I managed to install it! I am so pleased! 

[assause]

The OS version that CS3 is guaranteed to operate is up to 10.5.
Later operating systems are not supported.
Since macOS is an incompatible OS, it is impossible to run old applications.

[Test Screen Name]

Bear in mind CS3 cannot run in Catalina, even if you find a lucky break in Mojave. Apple have decide all old apps must die.