No personal experience with UCI direct.
Don't speak Italian either, but you can run any website through Google Translator or similar online translator.
The UCI website shown (above)
Ufficio Centrale Italiano/Polizze temporanee di frontiera
is (in translation) apparently only a UCI general administrative office/ website, listing only Italy office locations in major cities with address, tel, fax, but no email addresses. Website says to contact any of these local offices; displays no function to purchase Green Card thru this website.

Although Green Card prices may be more expensive through
Mototouring How does the European Green Card Insurance work?,
(or any of the other Euro Green Card specialty brokers in this thread),
the advantage is that you can apply/authorize purchase of the Green Card directly on their website(s), and even have the Green Card document mail delivered to you in advance of leaving for Europe.

If you're air or seafreighting a bike into Europe, you'll need the Green Card document in advance to present for Customs clearance. If your bike is already in Europe, you'll still likely save a hassle/ separate trip to buy the Green Card from a local broker office, if you obtain the Green Card in advance of travel.

It appears (to me) that, to take advantage of the lower prices quoted on the UCI website, you would have to physically present yourself to one of the Italy city office locations shown on the website--or speak Italian and call one of those offices. Even if you're willing/ able to do that, many local broker offices still require that you physically present your vehicle registration & personal ID to complete a Green Card purchase transaction onsite.