Hello.
The Business Small and higher versions of the Booking Calendar is support PayPal (Standard and PayPal Pro Hosted Solution (please note, PayPal PayPal Pro Hosted Solution its does not the same as PayPal Pro)), Authorize.Net, Sage Pay and iPay88 payment gateways integration, other payment systems are not supporting yet. You can configure and activate it at the Booking > Settings > Payment page.
You can check overview of different Booking Calendar versions at this page: http://wpbookingcalendar.com/overview/
Also you can test live demos http://wpbookingcalendar.com/demo/ to be sure in functionality and do not have misunderstanding.
Kind Regards.