KICAD_CONFIG_HOME
Base path of KiCad configuration files. Subdirectories will be created
within this directory for each KiCad minor version.
KICAD_DOCUMENTS_HOME
Base path of KiCad user-modifiable documents, such as templates,
Python scripts, libraries, etc. Subdirectories will be created within this
directory for each KiCad minor version.
Does the KICAD_CONFIG_HOME directory still exist in version 6?
Does the KICAD_DOCUMENTS_HOME directory still exist in version 6?
If so, where are these folders in Windows?
These do not exist, but, according to the description, KICAD_CONFIG_HOME is equal to %appdata%\kicad, and another one is “kicad” folder in “my documents” folder. Not at pc now, so may be inaccurate (different slash)
Edit, see eelik’s post below. It was new form me that these env variables can be used. I can make my kicad preferences portable now (put appdata to the cloud an run kicad with exact options on several computers, nice!)
KiCad uses that variable if it finds it. It must be a real external environment variable. It’s the way to let KiCad use some other than the default directory for the user configuration. Normally you shouldn’t need it. For v5 it was the only way to separate v4 and v5 configurations, and v4 didn’t recognize it. Now every x.y version has its own configuration directory by default, so the need for this variable is rare.
With this environment variable you can use other than the default location for the documents. It’s new in v6, so yes, it “still” exists.
As far as I know, the Windows installation doesn’t set these variables. KiCad just uses the default locations. What poco said about the locations should be approximately correct (I’m not on Windows, either) but how the question and the answer are set up may be a bit misleading. These variables don’t exist unless the user (or maybe the installation process) has set them. KiCad has an internal way to define the default location of configuration and documents, and these can be overridden with these variables.