Just wanted to know if there were a Mac version.
No, there is no Mac version of NaturalMotion Endorphin version because the developers have discontinued the application. If you visit the old link to the developer's website, something else will be displayed instead.
This was the official website: http://www.naturalmotion.com/middleware/
Here is an alternative: https://www.autodesk.com/products/motionbuilder/overview