It seems like he’s using a shortened version of this sample. In the Wavetable tab, use the Range Selection Tool to select just the first ~4 seconds of the creaking door sample.
Try using these settings for a result that sounds close to the original sample. Don’t forget to press the Set Markers button: https://i.imgur.com/y805ZcP.png
Play a very low key like C-1 on the virtual keyboard.
You can get a lot of interesting results by just importing random stuff into Halion and playing around with these settings.