I also noticed the problem of installing the XGBoost extension on Mac with this workflow (Binary Classification - use Python XGBoost package and other nodes to build model and deploy that thru KNIME Python nodes – KNIME Community Hub) in June and there is a ticket already in the knime system AP-20587.
There have been similar problems in the past AP-19894, AP-19918. I hope an underlying cause can be found and resolved.