Once the download is complete, open the dmg package just downloaded, drag the program to the folder applications macOS and open the last one, then right click on the icon Skype and select the article open to start the software the first time, avoiding macOS restrictions for applications from non-certified developers (there will be no need to do so later). To continue downloading Skype on your Mac, connect to the program's website, click Download from the main menu, select the option desk and press the button Download Skype for Mac. In fact, the famous program for making calls and video calls is not available in the Mac App Store as an application. The only solution to download Skype for free at Mac is to proceed through the official website of the program and start downloading the desktop client.