On your USB stick, place:
AutoCAD 2016 was one of the first versions to fully drop 32-bit support. A 64-bit version is mandatory for handling large drawings (over 2GB of RAM). When you search for "autocad 2016 portable 64 bit install", you are specifically looking for a version that: download autocad 2016 portable 64 bit install
In reality: Autodesk never released an official portable version. Any such download is a repack/crack made by third parties. On your USB stick, place: AutoCAD 2016 was