Apologies but I couldn't find this anywhere with the search -
I built from source on a headless linux box and have no interface other than a shell.
I have a license key for Makemkv , but can't find any documentation on how to license or a config file where I might enter it.
Edit: I literally found this while continuing to search , just minutes after I posted it.
The problem was that the ~/.Makemkv/settings.conf wasn't created automatically for me.
I manually created it and entered the key as such -
app_Key = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
and it works fine now. Going to leave this post though in case it will turn up in the search and help someone else