Headphones not working on Audiobox 1818VSL using Mac Mojave.... Absolutely Furious About This!!!

I just traded a guy a $900 guitar and my Focusrite Scarlet 2i2 for a fender amp and this unbelievably difficult to run Interface. I CANNOT EXPRESS ENOUGH HOW FRUSTRATED I AM WITH THIS RIGHT NOW. ​In all of my time using recording gear, I have never experienced a "help" forum more congested with so many unnecessary issues. I have a fairly new iMac and I upgraded the iOS to Mojave back in early Oct. I just got this interface yesterday and I have been searching the internet literally ALL DAY trying to figure out why my headphones will not work. I have tried everything they have suggested and nothing. If I don't get this figured out by the end of tomorrow, I am literally going to try to dish this off to someone else on facebook marketplace and buy myself a better Focusrite scarlet interface. WHY IS THIS THING SO FREAKING DIFFICULT TO USE?!?!