He’s off a bit there. They stopped the show with the end of Book 6, right before the time jump for Book 7. So they didn’t make the final 3 books into the show. There’s hints and foreshadowing for them.
Also the books don’t directly correlate with seasons until Season 4.
Book 1: Season 1 and first half of Season 2
Book 2: Second half of Season 2 and first half of Season 3
Book 3: Shortened and only the second half of Season 3.