If you just want to learn parametric modeling to get a job, learning Fusion 360 (Free for hobbyists) or FreeCAD (Open source) teaches you 90% of the logic you need. Once you get a job at an aerospace firm, they will pay for your CATIA license.
: Dassault Systèmes occasionally offers demo versions or trials of their software to allow users to explore its capabilities before purchasing.
If you still want to download CATIA V5R20 64 bits via torrent, follow these steps: