How can I get a live agent in chat to assist with a free trial activation
I don't think you can get live chat for that. Would try calling Sales at 800-225-5499 to ask. If your phone isn't unlocked and/or cannot run 2 different SIM/eSIMs then the trial won't work. You also cannot be using any Verizon services at all currently, nor be a customer of any of Verizon's subsidiaries such as Visible, Total Wireless, Tracfone, or Family Mobile. With Verizon having acquired Frontier recently, if you are using Frontier, you may also be locked out.