These "papers" verify that your part02.rar is not corrupted. You can generate these using tools like QuickSFV or HashTab .
v5.0.26139.0 (Often associated with the Anniversary Edition or specific season updates) File Part: part02.rar Format: RAR Archive (Part of a multi-volume set) Common "Paperwork" (Documentation) Needed Age of Empires IV v5.0.26139.0.part02.rar
This is the text document included by the release group (e.g., ElAmigos, FitGirl, or Razor1911) that contains installation instructions, system requirements, and crack info. You can view these using a standard text editor or a dedicated NFO Viewer. These "papers" verify that your part02