Use your official Autodesk account to sync projects. This allows you to log in to the installed version on any computer and pick up exactly where you left off, providing the mobility you might be looking for in a portable version. Conclusion
If you found a file called Autodesk Fusion 360 -portable-.rar on a torrent, file-sharing, or crack site, it is likely: Autodesk Fusion 360 -portable-.rar