I had same issue and finally figured out. You need to compare your MAC operating system to turbo tax system requirements. Even though I updated both Safari and Chrome to latest system requirements, it wasn't enough for Turbo Tax. Check your MAC operating system version by clicking on the Apple icon in the upper left hand corner, then select "About this Mac". In my case, my version is 10.9.5. When compared to Turbo Tax System requirements, the only browser version listed under 10.9.X is Firefox 65. So after I downloaded the latest version of Firefox browser, and entered Turbo Tax website and sign in info, I was able to get into Turbo Tax! Woohoo!
