Failure in a virtual machine

I want to deploy a virtual machine in the host but I have this problem

Can you help me?

Host key verification failed.

Looks like you’ve missed Step.4 Configure Passwordless SSH from the Node Installation Guide.

Hope this helps.

Best Regards,
Anton Todorov

I did this step and I have the possibilty to connect to host when I execute ssh .
Can you explain more where is it the problem in this step ?
Thank you for advance