How can we implement the RBAC using OKTA in .net core web project

how can we implement the Role based access in .net core web app using OKTA , as Okta deals with Groups and .net core with roles for Authorization.
I have referred the below OKTA library :
Okta.AspNetCore 1.3.0 for .net core 2.1 web app

Refered below link for RBAC , but unable to achieve through this.