By default, the invite will always send the user to the default canvas URL for your application. What you should do is detect this URL on the Index page, and then redirect them where you actually want them to go.
The way to do this is to look for the request_ids
in the URL ($_GET
) and then do a API call to /$request_id
to verify it. Then you can redirect the user to any page you want (either JavaScript redirect, or PHP header redirect).