Rustoleum insta post recreate help

here’s the link to the post I would love to recreate this as I happen to have 3 of these style shelves but can’t figure out how to attach the 3 shelves to eachother. It looks like zip ties but that does seems sturdy for indoor use also how did they attach the ropes to hang from the top tier?!? Help!!! I love this idea to add some greenery to my hallway!!!