It easier to answer question about a piece of code that doesn't work if you also include what you expect it to produce.
Just a guess but it looks like you want to produce 13 * 4 elements in your output, i.e. 52 the number of cards in deck.
But map and friends returns 1 output element for each element in the input so the map function you are using will return 4 elements in a list so you need an extra operation like this...
map(c("spades", "hearts", "clubs", "diamonds"), rep, 13) %>% flatten_chr(.)
This produces character vector with 13 * 4 + 52 elements in it.
This is an alternative syntax
map(c("spades", "hearts", "clubs", "diamonds"), ~ rep(.x, 13)) %>% flatten_chr(.)
which makes it easier to see what is happening with rep (just IMHO) because you need not know what map is doing with that "extra" argument 
If you are looking for some other kind of result just get back to us.