No need any workflow.
Hope you already added AD in both vRA and vRO.
If so very simple to search AD user or AD user group in vRA form.
Created one input "appOwner" and type should be AD:User . And in vRo presentation tab add "select value as" and set "drop-down "
You can application owner name in vRo by appOwner.name
Why have you marked your previous answer as the correct one if you're still having failures?
You're failing because you have an input type of your action of type Array/AD:User but you're not supplying that anywhere so the output is null.