Title is not a typo.
I have created an RMarkdown file and am only trying to render it.
> rmarkdown::render(input = "../models/SUPPLIER_NAME/SUPPLIER_NAME_20190820.Rmd", output_format = "html_document", output_file = "../models/SUPPLIER_NAME/SUPPLIER_NAME_20190820.html")
# Error: The directory '../models/SUPPLIER_NAME') does not not exist.
> file.exists("../models/SUPPLIER_NAME")
# [1] TRUE
Notice the error message is correct, it does "not not" exist. I am speechless.