As you can see in the error messages “Accessed None trying to read property Player…”. That means Player is null. That means you have a variable called Player, but it has no value. It does not point to anything. It should point to your player.
In the left side of capture.png, you have your variables tab and there you have your variable “player”. Press the grey eye icon next to it. This will make it accessible from the details panel in the game viewport. Go there and you should see a drop down where you can select a value for it. Assign the other car (player’s car) in the scene.