When running the Adobe Sign Get Signature action, you may receive the following Bad Request error message if an identity verification method is not allowed:

Bad Request {"message":"Signer identity verification method not allowed by account settings. ","correlationId":"xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_0_3"}. Error Code: IO.AsyncActionExecute.ErrorResponse]

See "Configurable options and defaults" section:

https://helpx.adobe.com/sign/using/signer-identity-authentication-methods.html