Avoid unofficial “Maya 2013 download” links. Instead, use current, legal, and secure software to learn or work in 3D.
Legitimate access is no longer available through Autodesk’s website, as the company only supports recent versions (via subscription). Current Maya releases offer vastly improved performance, Python 3 support, modern rendering engines, and security updates.
If you still need a short informational piece for reference or archival purposes, here it is: Understanding “Maya 2013 Download” – A Retrospective