extract the contents of the zip file you have downloaded. Inside there will be some other zip files. Look for the one named Creative_Sculptor.zip.
Go to Insert -> WebAssist -> CSS Sculptor -> Layout manager, clic kthe import button and select that zip file to import the Creative layout.
Now go to Insert -> WebAssist -> CSS Sculptor -> New CSS Sculptor page. From the designs menu, select the Creative layout to create a new page based on the Creative Layout