You can find an example in the templates themselves, it is the “Credits” slide and you’ll find it near the end of every CodeCanyon presentation. However, you can use another kind of attribution that fits your needs better: a mention with a link in the footer of one slide, or in the webpage if the presentation will be embedded.
Besides, be aware that I accept more subtle ways of attribution than the credits slide. For example a small link to CodeCanyon.com in the footer of the last slide in the presentation.
If you need to cite using APA or MLA format follow these examples:
- APA: Catalina, Jimena. (2020). Salerio Powerpoint template. Retrieved from https://codecanyon.download/salerio-free-presentation-template/1875
- MLA: Catalina, Jimena. “Salerio Powerpoint template”. CodeCanyon, 19 July 2020 https://codecanyon.download/salerio-free-presentation-template/1875