The .config folder is a hidden folder so you need some kind of Unix/Linux experience to get into it.

One way is to go to settings in FileBox and check "Show hidden files and folders"

Another way to get it is to open a terminal and type exactly this:

cp .config/scorpius/yappari.log MyDocs

And then a copy of yappari.log will be under MyDocs.

Also check you're running the latest version (0.0.16) because some previous versions had the log somewhere else.