Thank you for the link.
The development of PhantomJS has been suspended, according to the website.
The solution (with help from StackOverflow) was to use RSelenium to automate the web browser.
A general solution:
remDr <- rsDriver(browser='chrome', port=4444L)
browser <- remDr$client
browser$open()
browser$navigate("url")
Then together with findElement and clickElement or executeScript with more to get what you want from the dynamic website. Then
pagesource <- browser$getPageSource()
html <- read_html(pagesource[[1]])
And continue on with rvest.
A good tutorial can be found here.