Hmm...I had that same issue installing the latest version of Adobe Illustrator. What I found online was to revert my operating system back to an eariler version. The article said there is an installation issue with the newest version of Mojave on the Mac. I tried that but it wasn't working. In the end what worked for me was wiping my hard drive and reinstalling everything again. I'm not suggesting you wipe your hard drive and reinstall everything, but this worked for me. I believe wiping my hard drive worked because my Mac is six years old so I believe there was a lot of programs conflicting with the instalation process. Hope this helps.