It is not totally clear what you want to achieve here. From the text I understand that the user has a text box where he fill in something and then later on you want to convert that text to a label so you can display that on something else?
The Label Selector widget needs to point to a Label entity/attribute. So you could retrieve the text inp;ut, check if a label already exist and retrieve that one or create a new one and set the reference to that label object. Does that makes sence to you?
I think the CustomString widget (https://appstore.home.mendix.com/link/app/1426/) is the more updated version of what you want.
Set 'Render as HTML' to true, and in the microflow create the string you want to display. Have the end event return a String, in which you can enter the variable you created.
If you just want to show values of multiple attributes, then just use the text widget and use attributes as parameters
If you only want to show a single attribute value, an input widget can be set to editable: no + render as text (or use the text widget as well)
If you want to have it clickable; use a button, which uses the attribute value as label (optional, render it as a link)