This section describes, how to restrict the post type results to a certain category, or to multiple categories.
Advanced options -> Exclude results panel
Go to the Advanced options -> Exclude results panel and scroll down until the
Include posts.. option
Choose a taxonomy and the terms will load. Select the ones you need by dragging them to the left side of the box.
Save the options, done
By default, selected post type objects which are not associated with any terms will appear in the results list.
If you whish to exclude them as well, then trun OFF the
Show posts/CPM with empty taxonomy terms? option on the
Frontend Search Settings -> Advanced panel:
Tags: search in category, limit to category, limit search to category, include results by category, include from category only, limit to specific category, limit to tag, limit to post tag, search only in one tag, search only in term, search limit to term