autogluon: setup.py install does not work correctly

Code ran on Linux EC2 instance.

Our documentation on installing AutoGluon from source says to use python setup.py install, however, this code does not work to create a functioning AutoGluon:

git clone https://github.com/awslabs/autogluon
cd autogluon
sudo apt-get install -y python3-venv
python3 -m venv venv
source venv/bin/activate
pip install --upgrade pip
pip install --upgrade mxnet
python setup.py install

This code works:

git clone https://github.com/awslabs/autogluon
cd autogluon
sudo apt-get install -y python3-venv
python3 -m venv venv
source venv/bin/activate
pip install --upgrade pip
pip install --upgrade mxnet
python setup.py develop

Why does setup.py install not properly install AutoGluon?