...just because original repository stopped working and is no longer maintained.

• Go to https://bing.com/
• F12 to open console
• Copy/paste to console: cookieStore.get("_U").then(result => console.log(result.value)) and hit Enter.
• Copy the output. This is used with -U

$ git clone https://github.com/olaviinha/BingImageCreator.git
$ python3 BingImageCreator/src/BingImageCreator.py -U <authentication> --prompt <prompt> --output-dir <dir>