The 'View as slideshow' plug-in is for displaying your page in a slideshow form
select 'Enable' from the drop down menu
You have activated the 'View as slideshow' plug-in.
type [[slidetitle]] and then press the key 'Enter' on your keyboard
You will see the slide cover page template below
type [[slide]] and then press the key 'Enter' on your keyboard
You will see the slide page template below
Enter Contents
Enter Contents
select 'View as slideshow'
You will see your page in a slideshow form like below
There is another way to use the slide template
click 'Apply' on the dialogue
You will see the 'View as slideshow' template and can create your contents based on the template.