Civil 3d Portable: Repack
In short, Civil 3D is a resource-intense, registration-heavy, and legally protected application. This reality directly clashes with the very definition of a portable repack.
: Using a repack violates Autodesk's Terms of Service. For professional work, this can lead to legal complications and the inability to open files in official environments if the "cracked" version saves data with "educational" or "unauthorized" watermarks. Better Alternatives If your goal is to use Civil 3D flexibly or for learning: Autodesk Viewer : For simply viewing and sharing files without an installation, use the free Autodesk Online Viewer Educational License civil 3d portable repack