Hi, all. Last-minute--July 15--downloader here for TurboTax Deluxe 2019. I was having problems, too. I was able to download but not install. (BTW, I'm running MacOS High Sierra 10.13.6.) The application would download updates (no option but to do that), then when a pop-up asked me to install and relaunch, it would quit. I tried this 3-4 times; same frustrating result.
After trying again to get the program to open for me, I decided on a hunch to press and hold simultaneously the control-option-command keys just after the "install and relaunch" window popped up. While holding those keys down, I hit the install and relaunch button, and the program installed, finally.
I wish I could say I knew how this worked for my mac. Maybe it will work for yours!
