Civil 3d Portable [2021] -

Instead of using an unstable portable version, Autodesk provides several official ways to use Civil 3D on the go: Autodesk Desktop Connector & BIM 360 : By saving projects to the cloud via Autodesk Docs

To understand how to achieve portability, you must first understand why Autodesk doesn’t offer an official "Portable" version. civil 3d portable