Open by searching for it in Spotlight ( Command + Space ). Type "Papyrus" into the search bar at the top right.
If for some reason the font is missing from your system, you can download it from various reputable font repositories. Papyrus is free for personal use on most platforms. download papyrus font mac
If it appears, you can use it immediately in apps like Pages, Word, or Photoshop. Open by searching for it in Spotlight ( Command + Space )