I chose to uninstall docker (following instructions found here: https://therealmarv.com/how-to-fully-uninstall-the-offical-docker-os-x-installation/)
Then I installed docker-beta from homebrew:
brew tap caskroom/versions
brew cask install docker-beta
docker-machine create --driver virtualbox --virtualbox-disk-size "40000" --virtualbox-cpu-count "3" --virtualbox-memory "4096" default