Using Okta as Third Party Key Manager

I am just trying to integrate Okta as a Third Party Key Manager for WSO2 API Manager using the below link of document. https://github.com/wso2-extensions/apim-keymanager-okta

But i am getting the below error while accessing the API from API store.
APIAuthenticationHandler API authentication failure due to Unclassified Authentication Failure.

While validation token its giving response code as 200 but response JSON as {“active”:false}
FYI:
Using WSO2 API manager of version 2.2 update 7
Using Okta account https://dev-989795-admin.okta.com/dev/console

Thanks,
Anand.M