In order to receive an authenticated copy of a document present in this site you need to contact the local State Archive that holds that file: you may find the contact information in the section The Land and the Sources.
The authenticated copies, also called certified copies, are copies of the certificates issued by a Public Authority, which ensures its authenticity in accordance with the terms stipulated by Art. 18 DPR 445/2000.
Please remember that in order to receive an authenticated copy of a certificate you will have to pay an administrative fee, unless the purpose of your request (which you have to declare in order to obtain the copy) is exempt from payment. You may verify if your purpose is exempt from payment or not at the “Annex B” of DPR no. 642 of October 26, 1972.