Beamdog has announced the official release of a free HD Art Pack for download for Neverwinter Nights: Enhanced Edition for PC. You can get a copy (Windows or other OS) at the below link. The Windows (.exe) version will auto-detect which install you have (GoG, Steam or Beamdog), or you can install it manually if you want.

https://files.beamdog.com/

UPDATE: you can also find the latest Neverwinter Vault version, with some fixes, here:

https://neverwintervault.org/project/nwnee/hakpak/original-hakpak/beamdogs-hd-models-textures-pack-nwnee