I'm following your instructions and some of the terminologies used in your post above appears different to what I am seeing. I am using CSS Form Builder 2.0.1.
Also somethings don't make sense to me... for instance...
"For the Enter value option, click the lightning bolt icon, from the bindings panel, expand the Uploaded Files binding group, and select the Server Directory, then copy the server directory binding code and select the server file name binding."
I cannot click outside of the WA CSS Form Builder Popup box until I complete the form. So selecting anything in the bindings panel in the middle of that process is disabled.