Thanks for making this game! I was searching for a Godot game using Nakama to see how well it performs, and I came across this. I love how it just works, real-time.
Though, the controls were not very intuitive—it might have been intended, but I think that the tank sprite should indicate front/back the least.
While using the latest version of Firefox and I could not paste in the email, password nor the match ID, not even through the Paste button. I wonder if it's hard to get Ctrl-C, V working on it. Again, I'm no programmer, but maybe you should try using something like https://xkcd.com/936/ as was implemented on https://file.pizza/ because it looks cool anyway.
In the part where you define the least number of players to play with, “Find at least 2 players”, the word “players” is modifiable for some reason. I think it's counter-intuitive, especially for non-English users.
One last thing: the “X” button. It seems a little too small to have been noticed. Also, it may be misleading to use “X” in this case because X usually represents “exit”, not “back”, so the player may believe that the button is for resetting the whole game. Rather, you should name it with something that represents “back”, for instance “<” and place it in the top left corner.