Questions about the Nighthawk MR5100

Hello, I apologize in advance if this is a very stupid post but I am very new to this whole ecosystem and Im looking for some help. I am currently living in the middle of bum-f*ck nowhere, in need of gaming-capable internet, but there is 5G ATT coverage. So I figured I could get a 5G router (is that what they are called?) and a 5G mobile hotspot plan from ATT to get some decent internet running. I was planning on setting up the Nighthawk somewhere and running a LAN cable from it to my PC. Is this possible? Am I completely misunderstanding what these are used for? I need an external antenna to plug into the router, right?