I had same issue and this is how I solved it.
1) Created a text field called managerGet
default value is
Value[Key = "manager"]
Note Value is the Value in ADProp
2) Created second text field that will be displayed on form called singleName
default value is
substring-after(substring-before(managerGet, ","), "CN=")
Now I am trying to figure out how to take that and get the managers email address. Anyone have an idea? I went through the setup reference about adding GetUserInfo, repeating table and button. But I want it to populate a field to use when submitting.
Chris