How can I fix the 'Not Found' error?

When people submit a jotform, it shows them an error saying that the page isn't found. We receive the jotform, but the clients don't realize it. Please help us fix this error. Thanks.

I think you have figured this out already. The error is related to your custom thank you page URL which doesn't exist your website;

http://www.rhigolf.com/thank-you/

If you want to use a thank you page, make sure to create it first to your website.