For a semi-beginner, this is a really good start! Unity is difficult, even more so when you try to make a game in 48 hours alone. You did really well with some pretty cool art and a nice setup for a game. I would love to see more of this game! One tip is to make the export a little smaller, since I couldn't get it to fit onto my screen, even when I pressed fullscreen. I suspect the latter part might be an issue with the way Unity works with canvases and screen scaling, since the button disappeared.