You would start by installing the Hardware Support Package https://www.mathworks.com/hardware-support/kinect-windows.html
If that package does not recognize the xbox 360 in R2015a then there is little you can do.
I have reports that R2013a was able to talk to the xbox 360 at least partly, but certainly by R2016a that did not work at all. I do not know if it worked at all in R2015a: there is some reason to expect that it might have worked, but not with Depth or Skeletal or Tracking, just for color.
Microsoft deliberately made the second release of the xbox 360 mostly incompatible with PC programs, so if you do not happen to have the first release then you might not be able to get anywhere.
