This would only be allowed if the submittor provides a complete IP release for each of the design elements. I assume they did this. They've pretty much covered the territory though.
Honestly, I doubt that there is any permission for that. According to Google, for example, the "G" as a logo (as it is used here) may not be used by third parties. Google writes about this on their website: "Google G - Third parties are not permitted to use the Google G. It’s reserved for Google products and marketing materials."
So I'm really not sure how Adobe can approve this.
Font Awesome, Glyphicons and many, many others make social media icons available for use on websites. This is nothing new. If icons were so heavily restricted that nobody used them, then what would become of the social media channels? Just saying. Honestly, social media needs us more than we need them.
The file you referenced is limited to editorial use only (see under the limitations section below the image preview). While Adobe Stock does not accept traditional editorial content from individual contributors (traditional editorial is provided by partner agencies such as Reuters), we do accept Illustrative Editorial content from qualified contributors. The icons you shared are an example of Illustrative Editorial content and is acceptable without releases.
More information about the Illustrative Editorial collection can be found HERE.