I don't believe you need a credit card but, given the information I have provided above, you can find out from the folks on their discord server. I do not believe they charge people for using their service.

3Speak is a decentralized application (DAPP) utilitizing the Steem Graphene Blockchain. It is very similar to DTUBE, and yet better in my opinion. It caters to those that have been deemed persona non-grata by mainstream social media applications as I stated in my original comment above.

I have never seen any mention of the necessity to use a credit card. If you would like more information, I would suggest joining their Discord Server. There is also a great deal of information on the google form for application. I have provided the link above in my original comment.

As I also stated I am not a representative or team member of 3Speak. I just like the DAPP as it describes itself as being decentralized and unbiased.