Before addressing the "Portable" aspect, it is important to understand the technical advancements of the R26 release. Maxon focused heavily on unifying the user experience and enhancing simulation capabilities.
Using an unofficial R26 portable build comes with significant drawbacks: Cineversity | Getting Started with Cinema 4D Simulations maxon cinema 4d r26 portable
If you truly need portability, buy the Maxon USB dongle. If you cannot afford C4D, use the free alternatives: (fully portable via PortableApps.com, and completely legal) or Unreal Engine (free until you make $1M). Before addressing the "Portable" aspect, it is important
While not officially supported, some community members suggest a manual workaround for "semi-portability," though it still requires a valid license: Manual Copy : You can copy the installed Maxon folder to a USB drive. Re-activation Before addressing the "Portable" aspect