Alrighty...
I went to the help section, CSS Form Builder - Help Document, and clicked on Enabling/Disabling Form Elements. Is that even the right area I should be in?
Anywho, when it tells me to select the form element that will trigger the validation, then In the Behaviors panel, click the Plus (+) button and then select WA Validation Toolkit > Apply Client Validations > Enable/Disable Form Elements... there is no 'Apply Client Validations' option. So, I'm not able to finish this... that I know of.
What you told me to do... completely went over my head. I don't know what I would have to configure or anything....
Oh, and here is the link to the test section I made for this. It's the exact same form that I'll be using for the actual thing. testpage.php