Looking at that form, Results per Page is set at 999. If you want ALL, then in WordPress set this to -1.

There is only a search box in the form. Our plugin does not perform the text field search. That is handled by WordPress, which itself only searches Post Title, Content and Excerpt. That WordPress search behavior can be modified using plugins, such as Relevanssi, which is a free plugin, see here for details:

https://searchandfilter.com/documentation/3rd-party/relevanssi/

In the Relevanssi plugin settings page, you should find options to add the categories/tags/taxonomies/custom fields/custom post types to the search, and you must also then build the index in Relevanssi after you save those settings.