I am up and running! I am pretty sure I figured out what the issue was. Oh man, this is embarrassing...
So, I used the Terminal on my Mac to ssh into the server. However, what I didn't know is that I must have somehow lost the connection either from being away from the computer for too long and/or letting the computer go to sleep. So, when I would go back to continue with the tutorial I was no longer connected to the server, and thus when I was running the command I would see the error. I dunno, I think that's what happened. Anyway, that's my story and I'm sticking to it!