Update to Catalina
I have a Mac Air 13inch early 2014 version on OS 10.9.5 and I'm unable to update to Catalina. Nothing happens when I click install. I have 36 GB available space. Any advice?
MacBook Air
It's not clear to me whether you are attempting to launch the Install macOS Catalina app or not. After it finishes downloading, the installer app should be in your Mac's Applications folder.
To learn how to upgrade macOS to the latest version, please read How to upgrade to macOS Catalina.