SIM Card not from Verizon error

[AC Question]

I have an HTC One M9 and am now using the My Family Mobile plan from Walmart, which is powered by T-Mobile. I have never had service with Verizon, but getting a pop-up/error message that the SIM card is not from Verizon/unrecognized. So, I have phone service, can make and receive calls and texts but no mobile data..cannot connect to internet. What can I do to get rid of this error and gain internet access?