setting up Netflix Basic

Hi, thanks in advance.  I just switched us to a two line Go 55 account which qualifies us for free Netflix Basic.  I have Netflix "activated" in our T-Mobile account.  I have an existing Netflix account which I haven't used in a year.  Neflix recognizes me, but it asks me to sign up for one of their paid accounts and doesn't have an option to choose T-Mobile Basic at login.  Do I have to pick a paid plan and add my credit card?  If so, will I be able to switch that afterwards to the T-Mobile Basic account.  I've been on the T-Mobile support site and can't find this specific information.