I'm really happy you found your way to our little game and care enough to comment on it :)
Let's go over your problems from the easiest to the hardest to fix.
The help screen you saw at your first start can be accessed via the main menu (by pressing escape or the little cog icon in the top right corner) and pressing "Help", it just pops up at the first time playing so it doesn't annoy you everytime you start the game ;).
If you just want to play the game without any of the other bugs, i strongly advise you to use our non-web release of the game which is available on MacOS, Windows, Linux and Android. Just look for it on our itch profile or the description of the web build.
Also the game is designed for a 1920x1080 resolution, but i guess since MacOS applies UI scaling by default it doesn't fit on your screen. I can confirm that on my 13 inch MacBook.
The web release by itself only exists because some people were requesting it on Discord and isn't as thoroughly tested, it appears as if the scaling isn't working like on all other platforms.
However, there is a simple little hack around this problem: just scale the website via "command -" or the chrome menu.
Sadly, there seems to be a severe problem with our constellation of Godot version and MacOS version of Chrome, hence the WebGL context errors.
It seems to work just fine on Firefox for MacOS or for example Chrome on Windows, so if you'd still like to play it: please try the offline build or another browser (not Safari :D).
Hope i have been able to shed some light on your problems an you give it another try.