Hello @ashikai,
There is a shortcode which displays list of albums of all users :
[rtmedia_gallery media_type=album global=true]
However, there is not any shortcode available to list albums of a particular group as of now. I will discuss with other team members if we can introduce one for your requirement.
Regarding the documentation of media gallery, your request will be considered and we will definitely update it to make the content more user-friendly.
Thank you.