Italy Self Declaration Form - How to fill out?

My understanding is you do not need to do that form if you have done the dPLF. From the Italian government site. I added the holding for emphasis.

fill out a digital Passenger Locator Form (only in case of lack of necessary tools to fill out the dPLF, you can use a paper-based self-declaration) and present it to the carrier or any other authorised person, either printed or on your mobile device;

Thanks for the help Laurel!

Can you attach the direct link for reference? I'm still a bit confused since I downloaded this off the US embassy site on Italy travel guidelines.

Clara, fill the online survey on the Official site and pick France and USA as countries where you have been before entering Italy.

After you have answered the other questions about citizenship etc. You should see a page with these instructions:

Based on your answers, you can enter Italy. Read carefully the information provided below.
In accordance with Prime Ministerial Decree of March 2, 2021, Order of July 29, 2021 and Order of August 28, 2021 of the Minister of Health, people who have stayed in or transited Countries in List D in the 14 days prior to entering Italy must:
fill out a digital Passenger Locator Form (only in case of lack of necessary tools to fill out the dPLF, you can use a paper-based self-declaration) and present it to the carrier or any other authorised person, either printed or on one's mobile device.
present to the carrier, or any other authorised person, a certificate of vaccination stating that the cycle of vaccination has been completed with an EMA-athorised vaccine, or a EU Green Pass proving the same;
take a molecular or antigenic test, carried out by means of a swab and with negative result, in the 72 hours before they arrive.
In case of lack of the certifications under points 2 and 3 (which are not alternative), travellers may still enter Italy but they must:
self-isolate for five (5) days, activating local health surveillance procedures by informing Local Health Authorities.
get tested again, upon completing the prescribed self-isolation.
Travellers coming from Canada, Japan or the United States may enter/return to Italy provided that they are able to present to the carrier, or any other authorised person, a Digital Covid Certificate, or equivalent certificate, but they must take also a molecular or antigenic test in the 72 hours prior to entering Italy, carried out by means of a swab, and with negative result. Otherwise, travellers from Canada, Japan or the United States may still enter Italy following general provisions for Countries in List D, as described above (self-isolation and subsequent test).
The provisions described above are in force until October 25, 2021.
Border Officers in Italy may always request that you fill out a paper-based self-statement upon arrival.

If I were you I'd print out the dPLF and keep it in your carry-on bag.

Thank you for your question and for the responses. I believe we are in a similar situation having gone from Italy to Slovenia and on the 20th back to Italy. We will have been in the two countries for over 14 days and I was in the process of researching what we needed to do when I saw your question.