Query parameter on Fluent form

Hi,

I use Fluentform plugin, and I want to show a dropdown with CPT filter by custom categories I created with CPT UI.
I find this to help me : https://wpmanageninja.com/docs/fluent-form/advanced-features-functionalities-in-wp-fluent-form/post-selection-input-field/
but I don’t find the query parameter to do it with my custom categories. some of them are hierarchical.

Which query should I use to make it works?

Thanks for your help,

Regards