Question Related Tribe.so

I'm curious to know how Tribe.so allows creating redirected URLs within the comment section. I’d like to implement a similar feature on my website. Could you guide me on how to achieve this?

Like this: https://thankyou.tribe.so/l?u=http%3A%2F%2Fwww.skjennungstua.no%2Fguest_5.html&h=bf618184be4a673a514cf5cb870b6e42&source=answer&id=6585f41f58e088ad306f2e53