If you are looking for AutoCAD 2016 Portable 64-bit, it is highly likely you are encountering unauthorized "repacks" or cracked versions on third-party sites.
. Autodesk does not support or recommend installing its software on external or portable drives, as this can lead to software failure or inability to read hardware profiles. Official Alternatives to Portable Versions download verified autocad 2016 portable 64 bit
It is important to note that "Portable" versions of AutoCAD are not official releases from Autodesk. They are usually modified versions created by third parties, which can carry significant security risks or stability issues. If you are looking for AutoCAD 2016 Portable