Using findElements() in the RSelenium package to select multiple dropdown items and using clickElement()

findElements() creates a list of all webElements that were found. Therefore, you cannot use clickElement() on this list but you need to make a loop, like below:

library(RSelenium)

rD <- rsDriver(browser="firefox", port=4536L)
remDr <- rD[["client"]]
url2 = "https://www.fotocasa.es/es/comprar/viviendas/barcelona-capital/todas-las-zonas/l"
remDr$navigate(url2)
remDr$maxWindowSize()

# accept cookies
remDr$findElement(using = "xpath",'/html/body/div[1]/div[4]/div/div/div/footer/div/button[2]')$clickElement()

# click on Distrito
remDr$findElement(using = "class",'re-GeographicSearchNext')$clickElement()

# Find all checkboxes
checkboxes <- remDr$findElements(using = "class name", 're-GeographicSearchNext-checkboxItem')

class(checkboxes)
# [1] "list"

length(checkboxes)
# 10

# Loop for each checkbox
for (i in seq_along(checkboxes)) {
  checkboxes[[i]]$clickElement()
}