Put the app in a folder with your files, and double-click it.
Your files. Your family tree as a GEDCOM file (.ged), exported from Ancestry, MyHeritage, FamilySearch or Gramps. Two exports of the same tree? Put both in the folder, and the app lists the people it finds twice.
It asks for one thing. <meta name="papp-write" content="./family.json">
Or ask your AI for your own version. That’s the point.