here: https://training.plone.org/5/plone_training_config/instructions.html
I had to do
./bin/pip install wheel
before
./bin/pip install -r requirements.txt
otherwise you get
error: invalid command 'bdist_wheel'
To use C implementation of PyYaml you've to:
apt-get install libyaml-dev
for buildout to find yaml.h when compiling