How to install DASPI kernel extension?

[barnfry]

I've seen all the suggestions to install "DASPI kernel extension"

But I can't find a link to do this, or any reference to any such thing on any legitimate websites other than makemkv.

I'm sure I'm being stupid, but how do I actually install it?

(I am using version 1.7.2)

[Romansh]

There's a .pkg installer on the MakeMKV disk image.