The scriptable objects folder is located at:
Assets > ParallaxControlSystem > ScriptableObjects
The UPL_PopupDatabase contains a list of popups, which accepts objects of type UPL_UI_Popup. The Popups can be accessed by either matching the name of the Popups in the list, or by referencing the Popup element of the list.
Note: The UPL_Popup Databse can also be edited using the wizard: