FWCloud is a replacement for firewalld. Once you deploy FWCloud for your firewalls you no longer need to manage iptables rules using firewalld. In fact, once FWCloud is deployed in a firewall you must disable firewalld in order to avoid it from overwriting the rules set from FWCloud.
As you probably have firewalld/iptables rules already in place, you can use the import wizard of FWCloud to import all your current rules in FWCloud, check them in the GUI and once you are sure that the rules are ok, install them from FWCloud. After that step you must disable firewalld using systemctl.
Please, check this videos regarding the import wizard to get an overview on how it works on both single firewalls and clusters:
Please, let me know if you need any help regarding this.
We could schedule a demo to show you the main features of FWCloud and it can help you migrate from firewalld to FWCloud. We also offer training and consultancy services to help you in your deployment under that use case.