Open your DMG setup file.

This will prompt a pop-up with an error message that says "[Movavi Program Name] can't be opened because the identity of the developer cannot be confirmed."

Click the Apple logoImage titled Macapple1.pngin the top-left corner of the screen. A drop-down menu will appear.

Click System Preferences.

Select the Privacy&Security icon. Go to the General tab.

Click the lock icon and enter your password if required.

After that, click Unlock. This will allow you to edit items in this menu. 

Select Open Anyway.

Click Open when prompted and proceed to the installation.