In Firefox, apparently it is not starting on the first attempt, it is necessary to load and update the page to start correctly (I tested it on Windows). This may be because I am not using the latest version of Godot. Thank you for reporting this issue. I will work on a solution.
Oh, gotcha! I was able to play it in Chrome (seemed like it was the same issue, but your solution worked). I love the idea behind this game. Exploring a city as a drone is really neat.