Is it possible to play single player campaign? Or you are forced to co op

Hello, just downloaded this game with a friend and we both got same loading screen which says: authentication failed. Please help.

мне 32

网络是正常的 前几天还能玩 今天游戏都打不开了

I love this series. I have played all of the games and have had an absolute blast playing them.... up until this puzzle. I was trying to figure out what I was doing wrong the entire time I was in it. Thinking to myself that there MUST be a way to just press the walkie-talkie and have the other person hear the noises that were being made. The devs wouldn't force players to not only accurately hear sounds that all sound extremely similar but also produce those sounds for your teammate RIGHT? If it had been ...