How can I link the credit card payment to my square account setup?

You just need to link your Square account through our integration, the users will enter their credit card details and the payment will be processed through the integration and sent to your Square account. 

Here's also a guide that will help you setting Square up on your form: https://www.jotform.com/help/459-How-to-Integrate-Form-with-Square 

I hope this helps.