I followed your video tutorial precisely at https://www.youtube.com/watch?v=qYFnCPwEVZQ
I have the latest version of Pro, Forms etc, however, some things on my end are not lining up with your video, particularly your parameter formats like {{ url.param ({“key”:“departments”)} however when I follow this step on my end it inserts as {{dc:url:param key=“department”}} leaving me unsure where to enter the json_encode.
Screenshots of my set up can be found here: https://imgur.com/a/Js1xcJQ