Solution for programs that can not be installed on a Mac
Try to open the application that gives problems, probably the message 'Teamviewer comes from an unknown developer and can not be opened' appears.
- Open ▸ System Preferences
- Navigate to the Security & Privacy preference pane
- Click on the 'General' tab
At the bottom of this window the message 'Opening Team Viewer is blocked, because the program does not originate from a developer whose identity is known' appeared. Click on 'Open anyway' to still open the application.