Unable to Set AD:User via String Input or Other method.

We are trying to use the Out of the Box AD "Change a user password" workflow. But we are getting stuck at the trying to pass the Variable of AD:User via anything else like changing it to STRING without any luck.

The workflow works fine when we run it via the play button in VCO, it forces you to navigate and find the user in the AD tree structure. We would like to be able to just enter in a SamAccount Name to be able to tell it the proper user without using the TREE Picker. This would allow us to pass the Variable via REST to VCO from ServiceNow in a STRING format.

Thanks in Advance if you can point me in the right direction or tell me what I'm doing wrong.

- Casey