categorize media

I have used Document Gallery and Media Categories for a long while and updates few times. but one day my user said it cannot list the media files. And now I know that it is the media must attach to the page but it is no need before.
I used the code [dg category=en_cat-pdf] to perform this.
So is it any method to categorize the media files and show them on multi-pages?

https://ww.wp.xz.cn/plugins/document-gallery/