That was exactly our experience as well last fall on Riviera. My husband never went up to the desk to exchange voucher for tickets, I did for both of us every time. They take the vouchers and give you a ticket w a number.
WhatsApp worked for texts on Riviera Oct. ‘23. We were able to text using iPhones on Wi-Fi settings throughout the day as well. Keep in mind, only one device per room will have Wi-Fi at any given time. We did not have upgraded Wi-Fi.
I was recently on Riviera, two weeks in the western Mediterranean. We did not upgrade the Wi-Fi package and we were able to FaceTime w our grandkids daily. No issue. Enjoy your cruise!