Cosmoteer should support all the way back to 9_1. Plenty of people have cards that old.
In theory a missing feature should give a more informative error than that. In practice, DXGI_ERROR_DRIVER_INTERNAL_ERROR means that there was a driver bug that caused a crash, so who really knows, it could be a driver bug caused by a missing feature.
Z4GU3R0N does not have any settings.txt file in the folder
That file only gets generated if the game runs and exits without crashing. Try manually create a settings.txt file in your Documents\My Games\Cosmoteer folder and paste in the following code:
GameSettings
{
UncompressedTextures = true
}