It's the same workflow that you can download from GitHub - iansinnott/alfred-maestro: An Alfred workflow to execute Keyboard Maestro macros.
But with external trigger added:
@nikivi the external trigger is already there in the workflow. The only difference I see from what I have installed and your screenshot is the JSON Config inbetween the run and script filter. Is that what you are referring to? Can you take a screenshot or post what that is? Or even better just post your edited workflow?