If you are long time mac user then you already use downloaded apps on mac from other sites or even unidentified developers. On the previous version of OS X then was an option to allows applications to open from anywhere. Which let you run any downloaded apps from anywhere. But recently on the macOS Sierra apple has sadly removed this option. Which means you won't be able to install apps from anywhere or website than trusted developers or App Store.
How to Open Applications From Anywhere, Unidentified Developers, App Store in macOS Sierra
Now type your account password if you have and press Enter and done.
sudo spctl --master-disable
Just open System Preferences and go to Security & Privacy and go to General Tab.
And you will get this option back again.
Stay always updated with the latest news of Apple Stuffs. You can follow us on Apple News app, Twitter, add us to your circle on Google+ or like our Facebook page and subscribe to our Youtube Channel.