It's pretty good. About 2 hours long, and the ending was a holy shit moment. Nice and creepy too. Just how i like it. I do think this should've been in the game, but it's not like DS3 was incomplete. It did have 20 chapters and a conclusive ending. That's definitely not rushed.

Why you'd even use Origin in the first place baffles me. EA's knockoff version of Steam is nothing more than a con.

Go to the in-game DLC menu it's there.