Skeletal Mesh Merge Problem

Hi, I’m trying to merge my skeletal mesh together so I found this documentation but the problem is I encounter a problem where I can’t compile. I just copy-paste the .h and .cpp code to my VS2017. I also .change the project file instance to my project file name but I don’t think that the issue here.

The problem that I encounter (I do not know if there’s any more problem than this, because it just says that this problem) you can view it here.
I thought all the UE4 documentation’s codes are tested, but why this silly issue isn’t fixed?

Thank you.