Are you encountering a while extracting or is the DLC item not appearing in the Hunter's Dream?
: These files are usually for jailbroken PS4 consoles or the PC emulator. The user experience is often terrible. For example, an official bug report on the shadPS4 emulator states that for version 1.09 of CUSA00900 with the DLC enabled, the game "crashes on entering Old Hunter DLC". You can expect frequent crashes, corrupted saves, and game-breaking bugs.
This lack of official confirmation has only added to the mystery surrounding the file, leaving gamers to speculate and theorize about its significance.