Hello! I know that the Mac version is still kind of iffy, but also not sure if it's just for Mac, however when I try to make a new game, it won't let me overwrite so I had to click continue which took me to the character customization page. I went on to customizing my character but then an "UnknownError" popped up.
You mean when you first started the game it wouldn't let you create a new game? I think this may have to do with Mac's permissions with overwriting files, Can you try out this solution, to run the game like that, and see if it allows you to overwrite the file? If not, please go to the game's folder, browse to \Game.app\Contents\Resources\app.nw\save and delete both file1 files.
That should hopefully fix it!