In the past, international tickets purchased on Trenitalia's website required picking them up in Ita

I bought 2 couchette tickets on the TrenItalia website for an overnight train from Paris to Venice just a week or two ago for travel in July, but now I need to change my tickets. I was given a PNR code but no CP code, which apparently I need to change the tickets online.
The email receipt sent to me has our train number, seats, PNR Code, Master Code, etc... but no CP Code. The tickets are standard adult price tickets too... nothing special about them. I even registered on the website when I purchased the tickets, so I can look them up easily, but not change them because I don't have a CP Code
According to the website I should be able to change this booking quite easily, but I don't know why I didn't receive a CP code or how to obtain one. In fact, I can't even figure out who to contact at TrenItalia for customer service.
In the past, international tickets purchased on Trenitalia's website required picking them up in Italy at a station with a self-service kiosk. Perhaps that has changed. If not, you should have purchased calculate travel distances between cities from the French rail site since that is your departure country. Was there anything about retrieving your tickets calculate travel distances between cities at a kiosk?
Nothing about a kiosk. It says it's a "ticketless purchase" and that all I need to do is communicate my PNR code to the train personnel along with some ID to serve as my "ticket". So I guess this requires no actual ticket, per se.