How to send user to a form when button is clicked

I have a very simple app so far. There's no database or external process.  Just a few interfaces, with one that shows the content of a folder, given a folder ID.  I added a button to that interface that should send the user to a form where more files can be uploaded to the folder.  I created the below process model, which I'm calling with the below code. When I execute this code, the process stopped at the Document Upload without showing the actual interface.  No errors popped up either.  What am I doing wrong?

a!buttonWidget(
  label: "Add Documents",
  icon: "plus",
  saveInto: {
    folderId: ri!folderId,
    a!startProcessLink(
      processModel: cons!DSU_PM_DOCUMENT_UPLOAD,
    )
  },
  style: "PRIMARY",
)