Installing Apache-Airflow in Conda Environment

The error appears to be because async is a reserved keyword in Python 3.7 and this package has not updated their setup.py script. You can use Python 3.6 until the package is updated

conda create -n airflow pip setuptools python=3.6
conda activate airflow
pip install "apache-airflow[s3, postgres]"

I also had the same problem. I solved it by installing with conda instead of pip:

conda install -c conda-forge airflow

https://anaconda.org/conda-forge/airflow