"xfadsk2015 x64" (often appearing as xf-adsk2015_x64.exe refers to a "keymaker" or "crack" tool used to bypass the licensing and activation requirements of Autodesk 2015 software products
If you have found this file as a "free" standalone download, be aware of the following:
Without more specific information about what "xfadsk2015 x64 free" refers to, here are some general steps you could take:
Run the installer: