Problems with building app in app studio

Cannot pass dynamic values in to object body i was creating an app in active campaign’s app studio , well i had an requirement to pass custom values into body , which could be dynamic key values may be two or more when ever i passes two or more values it takes it as string instead of key pair values and there by on execution time the json in the app studios build config gets invalid cause the received data in the body is a string instead of key value pair

if u guys have any solutions that will be greatly appreciated