orig: https://xnanimation.codeplex.com/
XNAnimationMG.sln is VS2017 Community solution which contains xnanimation and sample projects.
When building content, one have to manually copy them to binary dir, ie XNAnimationMG\XNAnimationSample\Content\bin\DesktopGL*.* to XNAnimationMG\XNAnimationSample\bin\DesktopGL\AnyCPU\Debug\Content\