Unfortunately features like navmeshes or AI Controllers aren't supported in Cyberix as of now, but there are a few work arounds.
There are three possible solutions to achieving other AI car opponents. Place invisible cubes around the level, and when the car's xyz position matches the position of the cube (plus the radius of the width, height, and depth), then have the car steer a certain amount in whichever direction.
Another way is to again have cubes around the level, have a raycast on the car to detect those cubes, and have it steer the desired amount.
One more possible solution which is a lot more bare bones and potentially glitchy. Place cubes in the level that are the same height as the ground so that it doesn't interrupt the car's velocity, have the car steer when colliding with the cubes.