sharepoint online – Docusign REST API: Implementing OAuth Authentication using JWT Grant from Microsoft Flow

I am getting below error when making HTTP call for JWT Token,

The Authorization Call successeeded well as whown in below screenshot , but when making HTTP Call for JWT Acess Token (screenshot 2), then below error({“error”:”invalid_grant“,”error_description”:”unsupported_grant_type“}) as shown in screenshot 4 below.

I am new to using/developing Docusign for first time,so anyone kindly correct what iam doing wrong (like if i need to put/correct URL,Headers,Body,….. ) or plese guide me about what can be the error Cause.
Kindly Guide me, Thanks in Advance
Iam following below URL from Docusign OAuth Implementation
https://developers.docusign.com/platform/auth/jwt/jwt-get-token/

Step 1. Request application consent
Step 2. Create a JWT
Step 3. Obtain the access token –>getting Error @ implementing this step
Step 4. Get your user’s base URI
Step 5. Use the access token to make an API call

(https://account-d.docusign.com/oauth/auth?response_type=code&scope=signature%20impersonation&client_id=@{variables('IntegratorKey')}&redirect_uri=https://localhost1

https://account-d.docusign.com/oauth/token

https://demo.docusign.net/restapi/v2.1/accounts/@{variables('Docusign AccountID')}/envelope

Error screenshot