All options should be grayed out until you have selected any skin so that part is fine.
However the fact that the app isn't showing any skins is a problem.
And it is in fact using the exact the same value to populate the dropdown as it does when installing skins.
When you start the app and if it cannot find any Skins folder it should ask to create one. Did that happened to you?
Some options may also be disabled even when you can select any skin (depending on wich options it can read from the UserSettings.ini) but that's a later problem.