@santiespindd - There are some other posts in the 30-days category from October where they still haven’t had a response from the original owner of the heroku app that is being used in the challenge.
I am not sure if the 30-day challenge is defunct, but here are the other posts that mention the same issue
It appears @jetison made a comment years ago about missing emails from Heroku about this application and that is why it was shutdown but that was in 2022.
Hopefully tagging one of the people on record for this URL and its operations can assist you to getting it re-enabled.