Everything depends on the requirements of that script. If this should be added before the close body tag or in footer then use Insert headers and Footers plugin and add the script code http://prntscr.com/t6yvtv In case you need to add the mentioned script to the page content then you can use Insert JS element to add JS to page content http://prntscr.com/t6ywmj
So, first of all you need to get clear instructions from the script author about the place where it should be added.
