[jingai]

Do I just redo all of this on the machine, or do I need to uninstall python and start over?

All of those commands are intended for developers, and any of them can fail. Unfortunately, I cannot tell you where you went wrong without seeing the output from all of them. If you're really stuck, it might be best to start over and copy/paste the terminal output here (redacting your secrets/personally-identifying information, of course) so we can see what you're doing wrong.

Also, the git clone step is where I might have gone wrong. Isn't that a linux command? I'm on a Windows machine.

Git is available for many platforms, including Windows.

It's just one way of acquiring the source code. You could also download the ZIP archive and skip the git clone, but using git will make updates easier in the future (it's a matter of git pull origin master as opposed to downloading the ZIP archive and preserving your venv directory and zappa_settings.json file by hand).