Are you referring to this notice?
You can ignore that, as long as you validated your Theme Slider Revolution extension will 100% work.
Regarding the demo sliders, you can download it here and import it manually.
The imported slider might change alias and cause not to work if this happens please re-assign/re-set the slider. The banner slider on the Chruch Demo is set as Slider Settings: Above Masthead.
Hope it helps,