Without spoiling anything, Intermission (Yuffie’s DLC) takes place in the middle of the Remake storyline and basically follows what she’s up to before presumably joining the party in Rebirth.

I like Yuffie as a character, so I enjoyed playing the DLC. But you could probably find a Twitch stream or no commentary Youtube playthrough to catch up on the story if you don’t want to play it and not miss out.