Appointment booking is temporarily unavailable

Appointment booking is temporarily unavailable

Embeded Zoho booking page in my WordPress website. When someone starts a booking, after choosing time and date, an error appears before payment - "Appointment booking is temporarily unavailable due to restricted settings."

Used the embeded code given by the Zoho Booking. It's very disappointing to see there is no answer to this problem all over the internet. I hope replies to this question may help many in the future.