What is map file in GRASS GIS addon r.fuzzy.system and how it can be accessed?

I am inexperienced with GRASS GIS and I am trying to reproduce the fuzzy systems manual example. I am failing to load the MAP file, even if I wrote the ‘txt’ file with the rules and maps name.
Here is the manual example:https://grass.osgeo.org/grass78/manuals/addons/r.fuzzy.system.html.

What is a ‘MAP file’, how can it be accessed, and how do I use it?