• A Certified Email (PEC) mailbox: all businesses are legally required to have a PEC address registered with the Business Register.  

What if I don't have a PEC? Buy it from one of the suppliers in this list:
https://www.agid.gov.it/sites/default/files/repository_files/pec_pdf/elenco_pubblico_20170831.pdf

• A digital signature device:
  • a National Service Card - CNS (a card with a chip like a debit card) or
  • a USB token, a USB stick, available at the Chamber of Commerce.

ATTENTION: if your digital signature is a smart card, you will also need a smart card reader (available at low prices in electronics stores), and digital signature software, available at this link
http://www.agid.gov.it/agenda-digitale/infrastrutture-architetture/firme-elettroniche/software-verifica
If your digital signature is a USB token, you just need to insert it into your computer and proceed with the installation.