Title says it all. As a new player trying to unlock an allied race, I am absolutely lost. I have no idea where to go next.
I don’t believe the quest itself is a requirement (and it doesn’t block progress on other quests.) However, since exalted with Nightfallen is a requirement for the allied race unlock, you’ll get it done along the way anyhow.
Edit: Here are a couple of common things that can stall out quest progress on Nightfallen:
(1) Make sure the NPCs in Shal’aran have been fed, as they won’t offer some quests if they’re near withering.
(2) Some of the quests will require you to do the Leyline Bling achievement to activate all of the leylines to proceede.
(3) Make sure you’ve done any side quests in Suramar. Pretty much everything there ends up necessary for the Good Suramaritain achievement, which itself is required to unlock the Insurrection part of the quest chain.