If you did import complete pre-built website and forgot to install Slider Revolution plugin first (there is an information about required plugins before each demo installation process), you will get the message like
"oops... Slider with alias [slider-name] not found."
in place of where the slider supposed to be. In that case, you have to go thru import process once again, but this time, install Slider Revolution first and if the whole rest of pre-built website been imported correctly, choose Selected data only > Revolution Slider demo. Thus, the missing slider will be installed only.