Please don't worry; we have you covered. You can append the Audience URL with "?mode=login" as shown below:
https://app.webinar.net/849VTBzQ75q?mode=login
Using this URL, attendees who have registered for the webinar can enter their email addresses in the registered users area of the registration page.
For further assistance, contact us through chat or send us an email at support@webinar.net.