[Plugin: Network Latest Posts] how to set category in widget parameters

Hi, maybe I’m not able to find it myself due to my bad english knowledge.
Ho can I set “category(ies)” parameter in widget options?
I tried with shortcode, id, category name etc but I always obtain the same message:

Warning: krsort() expects parameter 1 to be array, null given in /home/ideamus/public_html/wp-content/plugins/network-latest-posts/network-latest-posts.php on line 417

I’m trying to show the latest posts of a specific category froma specific blog of my network.

Thank you very much!

https://www.ads-software.com/extend/plugins/network-latest-posts/