Although there is currently an option to integrate Zoho Bookings to Zoho CRM it's very basic and probably unsuable for most companies.
When you create a customer it does not take into account module layouts or mandatory fields in CRM so it will just fail.
Furthermore when creating an appointment in Bookings there is the option to choose a CRM customer. When you do this Bookings then incorrectly updates the CRM name. It sends the full customer name back to CRM updating the Last Name field with the full name and then deleting the customers first name.
I don't think anyone tested this integration to be honest.