If you are just trying to use MakeMKV for free (without buying a license) while it is in beta, you do not use the KeyDB.cfg file. Instead, you use the Registration Code :

The keydb.cfg file is a database of decryption keys used to open encrypted Blu-ray and 4K UHD discs. While MakeMKV normally downloads these keys automatically [11, 24], manual installation of this file is a common workaround for "Volume Key Unknown" errors or for users who keep their systems offline [15, 17]. Where to Place the File To use a manual

Based on your request, here is the content for the file used by MakeMKV. This file is used to bypass the AACS copy protection on Blu-ray and UHD discs.

is a popular tool that does exactly that—it rips and remuxes discs into MKV containers while removing encryption. However, MakeMKV relies on a built‑in decryption method that periodically becomes outdated, especially for new UHD releases.