Was this authorised by QNTM?

Doesn't need to be, the default license for SCP Wiki is Creative Commons BY-SA so you only have to attribute the source and distribute under the same license. I don't see that mentioned so it might technically violate the license unless they negotiated directly with qntm under a different agreement. That's the tricky thing with licenses, you never know if they have so unless the original creator is raising a stink you can't know and legally you have no grounds to object even if they are violating the license.

I think all SCP content is creative commons share alike (https://creativecommons.org/licenses/by-sa/3.0/), so I don't think he actually needs to -- assuming this is based on SCP and not the book. I know the book had some revisions done to make it legally distinct from the SCP stories for copyright purposes.

In one of the youtube comments the director says that they contacted the author and got permission.