Hello,
There are 2 ways:
– add shortcode of the form into the popup content, via Theme Options > Header Builder > Newsletter settings.
– create a static block, add the form inside using element, then select that static block in mentioned settings via Theme Options.
Provide temporary wp-admin access, so we can assist you.
Create an account via Dashboard (Users > Add new) with administrator role http://prntscr.com/s3rc9m > provide us with username and password via the Private Content area http://prntscr.com/s5mao7 You can use any email for it.
Regards