Comcast and Rhapsody - what type of account to choose?

Hi have signed up by comcast internet. I try to create an account with Rhapsody (Comcast provides free access for their internet customers) but if i select the "free plan" i was told that i can not select this plan. I do not want to subscribe for any of the other plans. If I select one of the others, i need to enter credit card etc. and i do not want to pay for it (Comcast should do it ;-)). I could not find a plan that says "Comcast plan" or so. What plan do i need to select without paying?

Thanks

Mike