You can check your booking here:
https://mm.alitalia.com/EN_EN/booking/apvsearch.aspx
To retrieve the booking on checkmytrip there is a corresponding PNR.
I was able to get this PNR when entering the original AZ PNR on AF.com
and looking at the end of the URL I saw another PNR which I used to retrieve the booking on checkmytrip.
Hope this helps.