the page noted above gets photos based on a set of user-defined parameters and displays them in a slideshow format. for example: https://jumear.github.io/stirfry/iNat_observation_slideshow.html?project_id=the-wilderness-center. if you go to the page without setting any parameters, it will give you some instructions on how to use the page.
here’s some information about setting parameters in the URL: https://forum.inaturalist.org/t/how-to-use-inaturalists-search-urls-wiki-part-1-of-2/63.
if you still have questions, please don’t hesitate to ask.