Syncing with an iOS device
You can sync BusyContacts with Apple Contacts on your iPhone and iPad.
BusyContacts runs only on the Mac but it can sync with the built-in Contacts app on iOS through a cloud-based service. If you were previously syncing macOS Contacts and iOS Contacts through a cloud-based service, your iPhone should automatically sync with BusyContacts once you've configured BusyContacts to sync with the same account.
BusyContacts will only sync contacts with an iOS device through a cloud-based service. BusyContacts will not sync local "On My Mac" contacts with the iPhone, nor will it sync with an iPhone via iTunes.