The most reliable way to own the full version is to purchase a used physical copy from marketplaces like eBay or Mercari . You will need a PC with an internal or external disc drive to install it.
Download the "NFS Carbon Widescreen Fix" from community hubs like GitHub to allow the game to run in 1080p or 4K resolutions. download-need-for-speed-carbon-game-for-pc-full-version
Need for Speed™ Deluxe Edition - Free download and play on Windows The most reliable way to own the full