Hi. I received a mail to accept the invitation. I accepted it. But I'm afraid I cannot make it on that day. What should I do? Is that mail just a confirmation email? Will they call me before interview to check if I'm available or not?

Hi. I received a mail to accept the invitation. I accepted it. But I’m afraid I cannot make it on that day. What should I do? Is that mail just a confirmation email? Will they call me before interview to check if I’m available or not?