[Pro Sites] Pro Sites - Free Sites

Hello,
I have set up a three-tiered option using Pro Sites (https://www.rocketbuilder.io/my-rocket-builder/). The lowest option is supposed to be a free option, but when you click on that one it asks for payment details.

Is there any way to avoid making people enter payment details for a free account? I can see it being off-putting otherwise!

Thanks.

Alex