String that represent vault path

Currently, I store all my zettelkasten notes in vault directory. Besides, there’s a subdirectory where I store autogenerated files created by double square bracket. So in “File -> Folder to create notes in”, I write the name of that subdirectory. But there seems to be no way to set “New file location” in “Zettelkasten prefixer” Plugin to make new generated Zettel notes stored in root directory. Typically, if I leave it empty, when I create Zettel notes, it also goes into the subdirectory. So hopefully, there’s a way to represent the vault directory itself when setting path.