Help! My Mac won't let me open BookCreative. What do I do?

It used to be that you could simply go into your Gatekeeper and select System Preferences > Security & Privacy > General, set Allow apps downloaded from: Anywhere:

But in Sierra, this option has been removed. Luckily, there is a simple workaround:

  1. After downloading an app from an unidentified developer, drag it to the Applications folder.

  2.  

  3. Select the app and right or control-click.

  4. Click on Open.

  5. Click on Open again to confirm you want to complete the action.