Find the prepared location within the Reet Slave Mines.
The location in question is a carpet located at -108.38, -111.89, 408.32 in the Reet Slave Mines. This is on the same level as Venril's Scale from the quest before, through the gates south of Venril's Scale.
Click on the carpet and you will receive some quest text indicating that this must be the place.
Examine the scroll you received from Enchanter Glowwp and further the dialog that pops up.