The redirect needs to be done on the body tag of the page, so the redirect will happen when the page is loading.
Please select the body tag and apply the redirect.
In addition , you will need to set the cookie value when the form is submitted. So when the form tag select, set a cookie a value (Behaviors -> Cookies Toolkit). This will set the cookie value when the form is submitted.
I have attached a working example which could help you with the steps.