As reported by Jens Goldhammer on https://community.alfresco.com/thread/226976 :
The Manager executable, used to start Tomcat, is missing from the Share installer.
This file has different names depending on the platform: manager-windows.exe, manager-linux-x64.run or Application Manager.app
It happens on all platforms, but on OSX you get an error too, because the installer renames it at the end, and it cannot find it. (See attached screenshot)