To own a haunted royal estate in BitLife, you will need to purchase one via the relator tab in the game. You can find this tab under assets and then relator or one of the variants that you can find under assets.
Click on the relator tab and then search for a haunted royal estate among the listed houses.
You will need to purchase one that either says haunted royal estate or an estate that is haunted. However, it's worth noting that the house's chances to show up may vary between games and characters.
So if you run into any problems with spawn rates, you might want to close the app or age up to refresh the listing until one shows up.
If you still don't find anything, just purchase a regular royal estate, but only if you have a large number of characters in your commentary or several dead relatives of your current character.
Doing so will give your current character a chance to have their royal estate become haunted by either an old character or a relative of the current character.
Because of this, we highly recommend filling up your cemetery full of old characters before starting the challenge for the best results.
Check out some of our other awesome Bitlife Guides!