Hello Marta,
Hope you are well.
Adding media files are better for images or videos. That is the default wordpress uploader. It is always better to use the upload system of wpdm. In that case, wpdm can affect some features of the uploaded file. That fixes many issues.
Yes with that shortcode you can add any category you want. For that you have to use the parameter categories
in that category slug.
Example:
[wpdm_all_packages items_per_page="20" categories="slug1,slug2,..." jstable=1 order_by="field_name" order="ASC/DESC" cols="title,file_count,download_count|categories|update_date|download_link" colheads="Title|Categories|Update Date|Download::155px"]
And yes search field, search only in the current category you are showing.
More details with all parameters, example and demo:
[wpdm_all_packages] – List all downloads in tabular format in a page
Thanks