On my iMac when I downloaded TurboTax2019 a +.dmg file" appeared in my "downloads" file. I double-clicked it and it gave me a pictorial file where I gently moved the resultant Turbo program from the box on the left to the box on the right which said "Applications." Then I discarded that file and looked in my true Applications folder and therein appeared TurboTax Premier 2019.app. Upon double clicking it I got the Apple message. Had to go to System Preferences and General and then permit my system to use the TurboTax program. That's it. I've never done anything fancy like doing your taxes after they were due. Good luck doing 2018 stuff!
