You should have followed the pip3 installation instructions, and have your cursor in a console window.
Type the following, then press enter…
pip3 install --user pybin
If this is successful you should be able to run…
python3 -m pybin
This utility will tell you if your path is properly configured. If it reports something like
The user bin directory `/home/cefn/.local/bin` is not in PATH
Type the following, then press enter…
python3 -m pybin put
This makes binary programs (that pip installs into its local directory) available as commands later.
You have finished installing and configuring pip3
You can now install the Vanguard Tools to connect to your Vanguard board over USB.