Wolfram Mathematica is software from Wolfram Research used for technical computing. The University of Michigan has various licenses for Mathematica depending on the user's University affiliation and the location of the device.
Mathematica is available free of charge for U-M faculty and staff only on personal computers. This is referred to as a "home-use license". If you're trying to install this on a university-owned computer, please see that section below.
This is a low-percentage event but is known to happen occasionally.
A university-owned machine that travels off-campus (such as a laptop) must use the "Mathematica for Sites" license.