How do I get the Thaldraszus storyline? I finished the other 3 zones and Forbidden Reach, but the quest to start Thaldraszus isn’t available. Don’t I need that to unlock world quests?
If you finished the other zones, you should have (or have available) a breadcrumb quest “To Valdrakken” which will start the Thaldraszus story quest chain.
I think you do need to complete all four zone story campaigns on your first character to unlock WQs (and the quest skip on alts).
By default (and original story line order), the zones are sequenced: Waking Shores → Ohnaran Plains → Azure Span → Thaldraszus.