You’re definitely on the right track. The best recommendation I have for this will be to download a Custom PHP text box from the link below (it’s free):
https://github.com/voidzone/php-box
After you download the box, install it and add it to the area of your template you would like. Then place the full PHP code from your slider into it (including the opening and closing PHP tags), save, and you’re finished. The image below shows the code to add.

Alternatively, you could just add a regular text box to the area of your template you like and use the regular WOW slider shortcode to achieve the same results. This way you won’t need to download any custom boxes.
Hope this helps.