ArcGIS 10.3.1 for Desktop is now available to students. Full hardware / software requirements are here but broadly you need a PC running 64 bit Windows 7, 8 or 10. Apple OSX is not natively supported though virtualised and BootCamp versions of Windows have been seen to work.
There is a form that must be filled in before you can have access to the ArcGIS install DVD. Once you have filled in this form then it should be given to your ArcGIS tutor
ArcGIS Student Copy Application Form
The software can then be obtained in the form of an ISO file which you must burn to DVD or install via a virtual CD drive (advanced)
Advanced users may want to install without burning a DVD by utilising “virtual drive” with Magic Iso
Once you have your DVD (or virtual DVD) you can use this PDF file to carry out the installation. Note: The procedure here is written for ArcGIS 10.1 – it may differ from 10.3 cosmetically but the procedure is the same.