Nothing is easier than getting rss separate categories. Let's analyze everything point by point:

1. go to admin
2. wp-admin.com.ua/wp-admin/
3. go to records -> rubrics
4. I refer to desired rubric and choose view
5. address will be something like this:
   https://wp-admin.com.ua/category/marketplace/
6. At the end of the address I write /rss or /feed:
   https://wp-admin.com.ua/category/marketplace/rss

That's all, a news feed of one category will appear on the screen and you can post from it to different blog platforms or social networks.. networks.

Good luck with development!