Images Piling Up Issue

Hi,
I downloaded the Classified Listing plugin (free version) and have been trying to add listings to the Listing Form. Everytime I try to upload new images for the various listings, as guest users, three things happen-
1) the gallery seems to pile up with all the images uploaded to the classified plugin (i.e all the entries ever created)
2) the uploaded images by the user don’t show up in the backend
3) by default there’s this default placeholder image that shows up as the featured image. I tried several times to delete this, but it doesn’t work. I have no clue why

Please suggest

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