[folder] is part of a Code replacement that organize the folder structure based on the camera serial number, it should look to the serial number and create a folder for the photographer and another to the camera, it's easier for me to identify what is what later in Capture One Sessions. The same code replacement takes care of all the metadata regarding photographer information.
It should be something like this:
RAW
Paulo
Z6II
D750
Martin
D810
D700