Shiny: Create zip file for download from files in folder

Question

I am building an app that generates several Excel files in a folder, "out/". I would like to then zip these files and allow them to be downloaded by the user. The names of the files are dynamically generated, so I am using a list.files function to build to list of files to be zipped. I tried following the advice from here, and while the app works, and I can see the CSV files are generated, the .zip file is not and the download offers me "downloadData" rather than the actual zip file.

Here is a reprex

library(shiny)
library(palmerpenguins)
library(tidyverse)

# Define UI
ui <- fluidPage(

    # Application title
    actionButton("button", "Zip!"),
    downloadButton("downloadData", label = "Download")
   

  )


# Define server
server <- function(input, output, session) {
  
  observeEvent(input$button, {
    
    #get list of names to loop through
    species_names <- penguins %>% distinct(species) %>% pull() %>% as.character
    
    #setwd(dirname(rstudioapi::getActiveDocumentContext()$path))
    
    # create CSVs
    for(i in 1:length(species_names)){
    
      species_check <- species_names[i]
      
      penguins %>%
        filter(species == species_check) %>%
        write.csv(paste0("out/",species_check,".csv"))
    }
    
    #download button
    
    output$downloadData <- downloadHandler(
      #zip name
      filename = "out/zip.zip",
      #generate zip
      content = function(fname) {
        files <- list.files("out/")
        for(i in 1:length(files)){
          name <- paste0("out/",files[i])
          fs <- c(fs, name)
        }
        zip(zipfile=fname, files=fs)
      },
      contentType = "application/zip"
    )
    
  })

   
}

# Run the application 
shinyApp(ui = ui, server = server)