Fast Draft requires OpenGL 2.0 or higher (with Shader Model 4.0 or higher on Windows), and at least 256MB of texture memory. If your GPU does not meet these requirements, these features will be disabled. more in here: GPU (CUDA, OpenGL) features in After Effects CS6 and After Effects CC | Creative Cloud blog by Adobe
if you meet these requirements and still having problems, try updating your GPU.
also, if you are trying to use Ray-traced 3d, know that it is obsolete, and as of CC2017 you can use the C4D Renderer that works on the CPU, gives better performance and is almost the same.