The lane lines aren’t a render output, NuRec renders RGB.
The structed lane data lives in map.xodr inside the USDZ. USDZ is a zip file, so you can pull out map.xodr and rig_trajectories.json. Parse the OpenDRIVE(pyOpenDrive/libopendrive) lanes gives you info.
We have not received a response from you in 1 month frame so we am closing this thread with the solution given. Feel free to re-open a new thread if the issue persists.