This cache is the physical BONUS of the Adventure Lab Caches - Harry Potter and the Deathly Hallows.
To play these Adventure Lab caches, you need to download the official app
Get the official app. Learn more.
Log on to the Adventure Lab app and help Harry Potter.
https://labs.geocaching.com/goto/GCHPATDH
At the end of your adventure you will receive the keyword to pass this checker.
You can check your solution with certitude.