Hi Tina,
No worries. We are here to help as much as we can.
The "Cannot retrieve the next object" error happens when you are using the next() method in an iterator and there is no object to fetch. In your case, it seems that the Google Drive folder name specified in the ROOT_FOLDER_NAME variable is not existing. Could you double check on your end if this folder is existing in the root directory?
If the issue still persists on your end, please provide your CID and the name of the script (Reply privately to author) so I could further investigate.
Thanks,
Vincent Racaza
AdWords Scripts Team