myTaxExpress and T2Express software update on Mac is different, because of the difference of computer system between Windows and Mac.
On Mac, first you need to remove/rename old software. Then you only need to re-download the latest Mac version software from our website, and move it under "Applications" folder. Your data files are under "\\my documents\mytaxexpress" folder, which will not be touched during this process. So you won't lose data file. The existing license key will still work as well.
After downloading the myTaxExpress/T2Express Mac version .zip file, latest Mac will unzip the file to an app folder automatically. If not, please click the mouse and choose "Open", it will unzip the software into app folder called "myTaxExpress<year>_mac".
You can find the myTaxExpress app software folder like the following. You need to move this app under "Applications" folder in latest Mac version and run it.