According to the RoboHelp help (Adobe RoboHelp (2015 release) )
Step 3 mentions two files that we can't find: wininet.lib and hhctrl.lib
Program Help for Visual C++ applications
This information is for developers connecting context-sensitive Help topics to C++ applications.
1)Open the project in the C++ IDE.
2)Add RoboHelp_CSH.cpp and RoboHelp_CSH.h to the project.
3)Link the wininet.lib and hhctrl.lib libraries to the application. Look for the hhctrl.lib library in the CSH API subfolder of the installation folder.
4)If you are using Microsoft Visual C++ with MFC, set the RoboHelp_CSH.cpp file so that it doesn’t use precompiled headers.
I checked in the installation and they are not there.
I found this previous post:
It sounds like the first file should just be available with windows. It doesn't mention where to get the second, but maybe try downloading the HTML Help Workshop here:
Otherwise, you might try contacting Adobe directly.
I chatted with Adobe Tech Support. The instructions for RoboHelp 2015 have been update in this PDF: http://help.adobe.com/en_US/robohelp/2015/robohtml/robohelp_help.pdf on page 343. The new instruction is: "Link the wininet.lib and Hmlhelp.lib libraries to the application. Look for the Hmlhelp.lib library in the CSH API subfolder of the installation folder."
However, there is a typo there and the file is called Htmlhelp.lib (with a "t" in it).