Continue to website redirects to blank space

Hi,

I’m using Optin Forms on my website, but after you fill in your e-mail adress, you get redirected to this ‘thank you’ page. It has a button that says continue to our website, but when you click on it, it redirects to a blank space. How do I get this button to redirect to our own website?

Kind regards,
Jolijn

The page I need help with: [log in to see the link]