Low for a single user, but high if you distribute it. Autodesk offers a free 3-year Startup license for students and hobbyists. If you use a cracked portable version, you violate the terms and could lose your legitimate free access permanently.
Install Fusion 360 locally on the host machine (with permission) and keep your project files on the USB. That is the fastest, most reliable "portable" setup. autodesk fusion 360 portable updated