Because Adobe typically supports the current version and one previous version, finding a compatible download for an older OS like Catalina can be difficult.
Launched around the same time as Catalina, this version was designed for 10.15 compatibility. The 32-Bit Problem: Legacy Versions (CS6 and Older) Is Mac OS Catalina 10.15.1 compatible with Illustrator 24.0 adobe illustrator macos catalina
Can't Install Illustrator on macOS Catalina - Adobe Community Because Adobe typically supports the current version and
This is the last major release officially compatible with macOS Catalina. adobe illustrator macos catalina
* Illustrator. * Questions. * Is Mac OS Catalina 10.15.1 compatible with Illustrator 24.0.