Thanks to Andy_mic in MSDN Forum, here's the answer:
Follow ALL the steps, step by step, in the following link: Deploying an Office Solution by Using Windows Installer
I ran into a couple of problems:
- I did not have the GUI Generator installed as a windows program. See this post for solution: Is Tools > Create GUID removed in Visual Studio 2012?
- The value for the Manifest in the Registry data of the AddIn should be: "file:///[INSTALLDIR]ManifestFileName.vsto|vstolocal". In my case the manifest filename was ABCAddin_v1_0_0.vsto and so the value has to be "file:///[INSTALLDIR]ABCAddin_v1_0_0.vsto|vstolocal"
- If you do not find the deployment and application manifest files in the "bin/release" folder, its because you need build a release version of the project first!