A variety of content is available from this platform. But in most cases, the content is usually derived from a book. You would therefore follow the style conventions for a book or book chapter.
For example, under the [Quick Reference] tab, if you choose [Diagnostic Tests],
You will see the ebook , Pocket Guide to Diagnostic Tests, 6e.
Another example of an ebook are the Case Files. If you read the copyright statement for each case, this material is classified as a digital book. Each case is therefore like a chapter in a book.
When the content is not derived from ebook, you probably will cite as a website, image, or video.