You can bring back the aforementioned 'Anywhere' option to the Security & Privacy panel in System Preferences with a quick Terminal command. Head to that panel and you'll see the blocked app listed with an Open Anyway button to create an exception and install it. When Sierra blocks you from opening an app, it lists the app on the General tab on the Security & Privacy panel in System Preferences. This opens a right-click contextual menu where you can select Open to open a dialog box that will let you override Sierra's reservations about its source. Next, press the Control key and click to open the app. Open Finder and find the app you want to install. If you can't allow apps to be downloaded from anywhere, then how do you download and install apps from developers with whom Apple is unfamiliar? I count three ways: 1. A third option - Anywhere - is no longer offered. If you go to System Preferences > Security & Privacy and click on the General tab, you will see only two options for Allow apps downloaded from: App Store or App Store and identified developers. Because sometimes you need to install an app that Apple can't identify but that you trust and know is safe.

It's now stricter with installing such apps than previous versions of OS X, but there are ways to get around Sierra's roadblocks. MacOS Sierra changed the way your Mac handles applications from unidentified developers.

App store not loading mac 10.12.6