How can I start maid academy quest line and there can I find it?)

You need to have read the information in James's place in the Underground City about the sacrifices being sent to Winterfall, so that Aura knows Richard is near there and that it has a high-speed regenerating barrier. Once you've completed Fortress of Wrath and rescued Mira, she'll be at the Trademond Adventurer Guild. Talk to her about Richard's anchor and she'll tell you that you need a Letter of Recommendation to get to Lord Trademond to try getting the Humilitas Rune from him, at which point the Maid Academy will be enterable.