The only professional portable solution: Install legitimate AutoCAD 2015 inside a Windows Virtual Machine (VirtualBox or VMware). Store the VM folder on an external SSD. Run the VM on any host computer (Windows, Mac, Linux). This is 100% legal, fully portable, and avoids all malware risks—provided you own a valid AutoCAD license.
AutoCAD 2015 "Portable" typically refers to unofficial, modified versions of the software designed to run from a USB drive or local folder without a standard installation. While these versions appeal to users for their low resource footprint and mobility, they carry significant risks and functional limitations. Autocad 2015 Portable
