Copilot Studio Action Unable to find author authentication

Hi All,

I am trying to call a power automate workflow using Action in a topic using author authentication.

But I am unable to find the author authentication in action properties. Please find the screenshot below.

Actually my requirement is I need to impersonate the end user who is using the copilot by using service account.

As I need to publish this copilot in my custom website and I am not looking for end user authentication.

I need to impersonate the end user using service account. Any suggestions and solutions on how to

 implement this requirement will be appreciated.

Regards.

Avinash.