How to extract a pattern from PDFs in R

I have several pdfs with dates in this format: 01.04.2020. I need to extract these dates. I am new to programming, so my knowledge is very limited. I tried using the keyword_directory function, where I am able to see which of the documents has the pattern, but it doesn't say which pattern it is. Only if it has or not.

Does anyone know about other functions I can use? Thanks.

result <- keyword_directory(folderwithpdfs, 
                            keyword = "[:digit:].[:digit:].[:digit:]",
                            surround_lines = 0, full_names = TRUE)