Not sure if this helps but if and when I change phones in the future I hope I find this to remind me.
Just in case anyone has the same issue with getting a new unlocked (not purchased through Verizon) Samsung Galaxy phone and is having issues getting some Verizon Google Play installed Apps to work here is what worked for me finally. Not sure if this same fix would work for other phones.
My phone works fine, my texts work fine so no issue with Verizon identifying my phone when I moved my SIM card over.
Downloaded Verizon apps, not working, tried a bunch of stuff, yada yada, called Verizon, selected Technical Support, accidentally selected one that that disconnected me to use a stupid chat app, called again, selected the "call me back" option (which was good since it was I think 30 minutes) got a person...and she was AWESOME!!!
She puzzled through it and ended up sending me a text that asked about setting up automated billing. Once I got it I selected the link in my text message, then canceled the setup steps for auto billing. Then tried the My Verizon app again and viola! Now it's working fine.
All I needed was the right link of some sort to connect me, note that the verification texts during initial setup of the phone didn't work. It only worked when I got the auto billing set up text.