Looks great! Low poly seems to be a great fit for this type of game.
I wonder, will the multiplayer gameplay be more akin to Rust and Unturned (Kill on Sight, Survival), or will the gameplay be more unique?
The Documentation looks great! Sure seems to explain most things, however you should go into a bit more detail on the PlayerMotorBehavior and the PlayerCameraBehavior, like you did with the PlayerStaminaBehavior. Would make things a whole lot easier on people.
A good recording software for straight up recording a desktop is OBS. Free and open source.
If you have a Nvidia GPU, Shadowplay is a good one, and AMD has a solution called ReLive. Both of those are included in graphics drivers.