1. Download myTaxExpress or T2Express Mac version software (a .zip file). Usually, it is downloaded in the Download folder.
2. Latest Mac OS will automatically unzip the downloaded .zip file in the Download folder; if not, please unzip it by right-clicking the mouse and choosing open from the popup menu. It will unzip the program in the same folder. Unzip creates an App, like "mytaxexpress2012_netfile" for the tax year 2012. Don't manually unzip into the Application folder manually, it must be unzipped in the original downloaded folder.
3. Since Mac OS Sierra, it's required that you move the unzipped App into the Application folder. For detail, you can also read this FAQ item.
4. Double-click the "mytaxexpress 20xx" icon from the Application folder to run myTaxExpress. If you encounter an error of "Unidentified Developer", please keep holding down the Ctrl key and right-click mouse on the App, then choose Open to run myTaxExpress/T2Express software.