If displaycal asks for argyll-cms, do not choose to download.
Instead, select "Browse" and point displaycal to your $HOMEBREW_PREFIX/bin.
displaycal is built for Intel macOS and so requires Rosetta 2 to be installed.
You can install Rosetta 2 with:
softwareupdate --install-rosetta --agree-to-license
Note that it is very difficult to remove Rosetta 2 once it is installed.
