I have tried following several of the guides available out there with no success. Tried using BG3 mod manager as well as Vortex. I do so wish Larian would get on the ball of give us mod management.
In the mean time I have had to revert to manually editing the modsetting.lsx file. This works for most mods.
There are a few exceptions, such as mods that replace or add to the game files like the script extender.
I would even be happy with a program that would take a list of *.pak files and create a modsettings.lsx file from it.
