I’m not sure what nVidia Geforce has to do with any of this.
Region assets are simply a config.txt file and a thumbnail image, so they do not need a powerful computer to make. However, if you don’t have a version of Trainz installed on a computer that can run it, I don’t see how you can get your Region asset into its Content Manager database and actually used in the game, or uploaded to the DLS so others can use it too.
Also, you don’t download Content Manager, it is built into the Trainz program.