How does "Deep Palace Song" trigger Atan's plot?

Step 1: Open the Deep Palace Song Game, and click the place indicated by the red arrow to enter Fengtian Building, as shown below:

Step 2, pray for more than 10 to trigger the plot, as shown below:

Step 3: Click the "Discussion on Atan" indicated by the red arrow, as shown in the following figure:

Step 4: Click Yes to trigger Atan's story of entering the palace, as shown below: