From what I was told by customer support, Zoho Books does not allow you to collect payment without disrupting the sales process. There is no way to collect it via API, there is no way to import it via merchant. You can either email the customer to enter the card info or you can manually enter it in yourself. I'm hoping someone here may know of a way to add card information to Zoho Books aside from the options I was given.

I just can't believe the only way to collect credit card information is by disrupting the sales process or manually entering it.