To open a popup menu you can simply write a LocalScript that subscribes to the item and opens the popup window - add the attached code to a new LocalScript replacing the original module.run method. Then, rename your popup to "my-popup" (or change the name in the config part of the script) and configure everything else in the script in the config part.
A quick note: as your HMI can be opened on many different browsers at the same time this has to be taken into account - depending on your implementation you probably want to close the popup on all browsers once something has been done on one of them maybe to avoid confusion.
