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

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

({variables('IntegratorKey')}&redirect_uri=https://localhost1{variables('Docusign AccountID')}/envelope

Error screenshot