it definitely exists: https://acme-v01.api.letsencrypt.org/acme/authz/owQWEx8raxoV8iV4-jcsWX4bT_l78EDzPcYO9zkQB-I
That ', at the end of output the looks super suspicious and is probably the reason that the tool is giving a 404. Perhaps check your input files and strip the ', away to make the tool work.
I wrote a similar tool here here if you continue to have trouble.