Installed Python 3.6 also (using an external apt-repository) and configured it to use those paths:
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt-get update
sudo apt-get install python3.6

export PYTHONPATH=/usr/bin/python3.6
alias python=python3.6
$ python --version
Python 3.6.12
However conda still uses the latest Python version on my system. Don’t yet know where that is configured. The conda install still fails and prints: “Your python: python=3.8”