www.makemkv.com

I will let someone more experienced than me check the log (it looks like you've got a download error as well ?), but I will say that as far as I know the KEYDB.cfg file (which is supposed to be placed inside the MakeMKV config folder, as you probably already know) does have a key for the 4K ...

Just got my first 4K UHD bluray and wanted to rip it with MakeMKV just as I did with my other normal Blurays.
But I got some errors with the decryption it seems.
So I made an account just to find some help :)

This is the drive I got:
Drive informatie
Naam OS-apparaat: E:
Huidig profiel: BD-ROM ...