Can't enter pvp from duty finder

[Yui_Tenshi]

Conjurers may specialize into white mage once they reach level 30, and complete through the quests "Sylph-management" (main story quest from Minfilia at The Solar (X:6, Y:6)) and "In Nature's Embrace" (conjurer class Quest from E-Sumi-Yan at Old Gridania (X:6, Y:10)). And then you may take on and complete the white mage job quest "Seer Folly" (from E-Sumi-Yan at Central Shroud (X:25, Y:27)). That will give you the white mage Soul Crystal to equip for that job.

[Niwashi]

... white mage job quest "Seer Folly" (from E-Sumi-Yan at Central Shroud (X:25, Y:27))

The quest is picked up in Old Gridania, at the conjurer's guild. It then sends you to the South Shroud. All of the ARR job unlocking quests start at the guild hall of their corresponding class, and then send you to wherever the remaining job quests will take place. So you pick up the initial WHM quest at the conjurer's guild and pick up the initial SCH quest at the arcanist's guild, and so on. (Just remember where they then send you, because wherever that job unlock quest ends is where you'll need to go back to each five levels for the next few job quests.)