Mac: App can’t be opened because it is from an unidentified developer

I get an error that says "Sidekick can’t be opened because it is from an unidentified developer"

Solution:

You'll need to allow apps not found on the Mac App Store install on your Mac. It's super simple.

Go to System Preferences—> Security and Privacy? 

Click the lock to make changes.

Make sure that “Mac App Store and identified developers” is checked in the security preference.

Click the lock to prevent further changes and close System Preferences. You should be able to install Sidekick successfully now!