Please let me know what resolution/aspect ratio you were using so I can test it in-editor as well as re-anchor the canvas elements.
The zombies not attacking.. I actually noticed this just hours after the deadline! This occurs because the slower zombies think they've "reached their destination" so they stop moving, but they haven't moved close enough for the player to enter the trigger collider to deal damage to the player! As far as the crash you experienced, I've seen others report this as well. There is a crash that occurs when dying that I am looking into fixing.
Thanks for playing!