How to install:
1. Copy files from archive to your store.
2. Add Italian language in Admin - Locale - Languages:
Language name: Italian
ISO Code: it
3. Interface translation pack installed. You can change interface language at Admin - Account - Prefences.
4. Define content translations in admin for categories, products, order status, email templates, product labels, etc...
5. Clear cache in Admin - Configurations - Store Settings - Reset cache button at bottom right.