I have configured a simple test approval form to route a document to the manager. Neither the admin submitting the form nor the manager have named user licenses. In configuring the User Task in the process modeler, I specified the LF user account of the admin staff who would be submitting the form, then attached her email address via the Web Admin Console as directed in the help files. I also included my own user account/email (and I'm an admin and have a named user account). In "Notifications" I checked "Email task participants...". 

For testing, I submitted the form and while it shows up in my Forms Inbox, neither myself nor the other staff member received an email notification.