Can someone please tell me what to do to make my monitor arm usable? I got it off NextDoor with the guy saying I'd need to buy Vesa plates but the sockets don't look like they fit any Vesa plates I know. I've tried looking up what this clasp thing is so many times and I've become desperate. the arms are dual monitor arms from eveo but they don't seem to be the same clasp piece as what they show. Their tech support basically shunned me and refused to help, presumably cuz I'm not the original owner.