The folder $KSP/KSP_Data referenced in CONTRIBUTING.md does not exist (at least on win10-x64) and should be replaced with $KSP/KSP_x64_Data.
Most of the dlls CONTRIBUTING.md asks you to copy from $KSP/KSP_x64_Data/Managed do not exist (at least on win10-x64) and do not appear to be referenced by kOS.
CONTRIBUTING.md does not mention .Net Framework 3.5 installation.
CONTRIBUTING.md should instruct the contributor to, upon first opening the project in Visual Studio, right click on the kOS solution and click 'Restore NuGet Packages'.