This is a copy of my answer to your question on Stack Overflow.
You’re in the wrong repository. Those Python files are for Digi gateway products.
The XBee 3 products use MicroPython, and you’ll want to make use of the xbee-micropython repository instead. Per the README for that repo, you might also want to use the Digi XBee PyCharm IDE Plugin for development.
Tom Collins is correct and I should have caught it. You are using the Python repository for the Gateway products and not the Micro Python repository which is for the Modules.