Issue when requesting api embedtoken

Issue when requesting api embedtoken

I am making an api request.
  1. /api/v1/requests/{REQUEST ID}/actions/{ACTION ID}/embedtoken

And I get an error
  1. {\"code\":1011,\"message\":\"This account does not have the permission to sign the document\",\"status\":\"failure\"}

I have a trial account

What is the reason for the error?