According to the startpost you have to go to options and set it to "Ultra". I can tell you though that the mod works with any kind of settings. I haven't touched mine (they are more or less "high" with a few custom settings here and there) and the mod works like a charm. So...actually you're good to go. Just play. Most obvious thing to notice and to make sure the mod works: Drive a vehicle at night and look if static objects and pedestrians show shadows when you drive up to them.