Thank you!
The Xora's Vial is designed for a single player and not guaranteed to be pretty with more than 1 PC though there are several NPC travelling companions that you can pick up over the course of the module. I believe the multiplayer was referring to the PW since it mentions the servers later.
Xora's Vial takes place in Layonara (as we know it) in the year 1388, so approximately 15 years before Sinthar Bloodstone's defeat.