The webpage says this: "Selo and Mangler Progression Servers As we come together to celebrate this momentous anniversary, it's the perfect time to begin a brand new adventure in Norrath and relive the earliest days of the game. Players will be given TWO new opportunities to reexperience EverQuest's history when the Selo and Mangler Progression Servers launch on Saturday, March 16, 2019 at 12 AM PT!" That was 7 hours ago.
So the webpage was a typo. They need to fix that. (https://www.everquest.com/news/eq-20th-anniversary-celebrations-2019)