Hi,
After enabling the module, it put me a wrong Tag Base URL on admin/settings/calais_marmoset. It was:
http://mysite.org/enmarmoset
That URL doesn't work on my site. I think "en" before "marmoset" is because I am on a multilingual site, which it's default language is not English, and I am browsing in English. So I changed the URL to this:
http://mysite.org/marmoset
which is a valid URL on my site, and saved the configuration.