Each user-password web application typically requires its own set of fields in an HTML response. The help text for the generic user-password application template describes how to use a browser to discover these fields in Discovering the login URL and form data fields. You may also use other HTML POST analysis tools to discover required fields.
Most user-password applications require only a user name field and a password field. Each application typically uses its own pair of field names for these fields, though, so it takes some customization to correctly set up the custom user-password script. The POST analysis may reveal extra required fields for a very few user-password applications. You may be able to guess what these fields must contain by their names and supply the proper values, but if not you’ll need to contact the web application service provider’s technical support or development team to ask for details.