Third: send your application! Pay attention: the deadline is January 21st, 2022.
First of all you have to choose how you want to send your application. Here are the two possibilities:
Electronically, necessarily by your *personal* certified email address (the so-called "PEC"). In this case you have to send all your pdf documents as attachments from your own personal PEC address to the PEC address matematica@cert.uniroma1.it, with subject "Candidatura alla procedura comparativa Bando AR n. 8/2021".
By ordinary mail, which should compulsorily be a registered mail with return receipt ("avis de réception"). In this case the envelope shall be addressed to
Al Direttore del Dipartimento di Matematica "Guido Castelnuovo"
Sapienza Università di Roma
P.le Aldo Moro, 5
00185 Roma - ITALIA
Moreover, on the envelope you must also write the formula "Candidatura alla procedura comparativa Bando AR n. 8/2021".
If you choose Option 2), then put all of your pdf files in a pen drive, put the pen drive in the envelope and send just this!
It might be safer (and recommended, indeed), in case of Option 2), to also print the application form in plain paper, sing it, and put it in the envelope, just in case something goes wrong with the pen drive.
How to obtain your own PEC.
If you choose Option 1) and you don't already have your own PEC email address, you need to create it.
In order to obtain a PEC address, you will only need to visit a provider’s website and follow the instructions to open a PEC account. Usually, you will need to insert your personal information, then upload a copy of your identity document, and of your Italian tax code (not always). You will then need to choose an address (e.g. yourname@pec.it) and a password, just like any other email account. Often, in addition to traditional access through the website of the provider, you can log into your PEC account, send and receive PEC emails through an app.
There are several companies that offer PEC accounts. Usually, they all ask for a monthly/annual subscription. Costs start from a few euros per year (you can have a PEC address for 5 euros + VAT) for a basic PEC account, which generally includes a limited space for your email (for example 1 GB) and antivirus. Obviously, the more services you want (more space, storage, etc.), the higher the cost (for example 25/40/60 euros etc.).
Just to list a few, the most used ones are the following: ArubaPEC, Postecert, LegalMail, Register.it, Libero, ...