Unable to access purchases/subscription Google Play API

The following error occurs as I try to access purchases/subscription endpoints of Google Play:

{
    "error": {
        "code": 401,
        "message": "The current user has insufficient permissions to perform the requested operation.",
        "errors": [
            {
                "message": "The current user has insufficient permissions to perform the requested operation.",
                "domain": "androidpublisher",
                "reason": "permissionDenied"
            }
        ]
    }
}

The following configurations are already done :

• Service account with permissions are created
• Service account email address added in license tester section in playstore
• Enabled google play apis in Google Play Console

Below troubleshooting steps will help you to resolve your issue:

1. If you are using Play Developer API, the publisher was trying to authenticate as an end user Only users (or service accounts) that are granted the following permissions in Play Console can make Play Developer API requests. Play Console Permissions required to use Play Developer API (dev site):

• View financial data, orders, and cancellation survey responses

• Manage orders and subscriptions

2. You need to add the service account email in the "Users and permissions" section of Google Play Console and wait for 24-hrs after adding the user in Google play console.