Skin Creator doesn't work with the Incredimail application because it hasn't been updated to support newer versions. When I try to access the official link that points to the download page, the domain redirects to the gallery and that's it. There is no trace about the software package or something similar. Because of this, I can say that Skin Creator is now a discontinued application.
Additionally, its interface looked like the one in Windows XP, and in 2017 we have Windows 10 which is a major leap from XP.