Regretfully, UberMenu popup is not a feature offered in the header builder. It could be possible with custom development but that would be outside the scope of our support. We do have an in-house custom development team that offer paid services, who may be able to assist. They can be contacted at email@example.com if this is of interest to you. If you have any further questions about the theme, we are more than happy to provide you with assistance on these inquiries.
Thank you for your understanding.