Securing Web service with Okta

I am new to Okta, still reading documents and going through samples.
So we have a web service used by our applications (some of them are Web and most of them are Windows application )

How do I implement Okta authentication for this Web service?
We want to authentication each web service call against allowed user AD-group.
This could be trivial but I just want to get basic idea, how to approach this?

Hi @viks

The easiest way to allow both web users and Windows users to log in to your application via Okta is by implementing Resource Owner Password flow. After the authentication, the user receives an access token (and an ID token if specified) that you can verify on your end and, if it’s valid, then the user is granted a session inside your application.

It helped. I think I am on the right path now.