MacBook Pro Model A2918 - Connecting 2 Monitors

Hi All,

I have a work MacBook Pro, I just purchased a second monitor to increase my work flow. But I'm having problems, the second monitor turns on but just mirrors the other display. I have it connected to the MacBook with an adapter that feeds the two separate HDMI cables into one lightning cable to connect to my Mac. Is it that I need a better adapter? Just kinda lost because before I purchased the second monitor I checked online to make sure it was compatible and it said it was. But now I'm also finding mixed reviews with some people saying it won't work. Any insight into the problem would be appreciated.

Another note - I've tried to have them connected separately by connecting one of the HDMIs straight into my computer and the other one thru HMDI to USB-C adapter and to no avail only one screen will stay on