The add-on displays all the quests of a map zone at the same time. For some quests to be available there first has another quest to be completed though (so the story has the correct order, obviously).

While it would technically be possible to incorporate this behaviour in the add-on, there are at least two reasons why I haven't done this yet:

• It is very tedious and time-consuming to collect, update and verify all the quest dependencies (this has to be done manually as ZOS doesn't provide that information)
• Wrong and/or old dependency data might result in not displaying quests that actually would be available in game and thus may let the player miss those quests

Because of these points it's smarter to display all quests together as of today. I hope I can add this feature some time, maybe I could add another map filter for quests that are not yet available so the user could decide which scenario he likes better.

Update: My add-on for collecting quest data (Quest Map Scout) can detect most follow-up quests now (as long as the user doesn't leave the NPC dialog between completing the perquisite quest and starting the follow-up quest). It takes time until I have enough data and formatted it correctly though.

Also check out this related question.