This is an issue on some browsers/computers. To fix it, simply press Ctrl++ or Ctrl+- (pressing Cmd instead of Ctrl if you are on MacOS) as many times as required to resize the game.
Zoom doesn't work. Why?
You likely did not have an active internet connection while opening the web app. This will prevent the jquery script from being fetched, thus removing the zoom plugin's functionality.
Try connecting to the internet, reloading the crossword page (or loading a new crossword and opening it in a new tab), then try the the Zoom feature again.
pip/python doesn't work when I type it into my terminal
Ensure you are using the "right" python/pip, which may be python3 or pip3.
Alternatively, read installation to install Python or pip from scratch.
I opened the web app and the crossword game did not appear
You may have opened the web app without a browser open. Because of this, the browser may forget that it has to open a new tab with the crossword. Try pressing Open once more, or manually enter the address to the crossword game, which defaults to localhost:5000. The port may be different, if so, open the file at the path: <documents-dir>/xpuz/config.ini to see what your port is set to.