Sorry for the delayed response, but local should be located under the assets folder (at least for me; I'm not sure about you). like the image below
Therefore, when opening the local files, you ought to see a number of folders you are familiar with; nevertheless, let's disregard that and look for PizzaTower_GM2, which has a folder named levels.
simply place the appropriate pltv file in the folder, launch the editor, and presto! You have it now!