HPL3/Resources/TDD Asset Pack
The Amnesia: The Dark Descent Asset Pack has been released on Steam.
You can download it and put it in your mod to use it, but it would be recommended to instead use a mod dependency. It might not be possible for Amnesia: Rebirth, because the asset pack is released as a SOMA mod.
To do: Test if Rebirth can use a SOMA mod as dependancy
Further reading: Importing HPL2 assets to HPL3