Implement Oauth2 in Google data studio

I have implemented all the required code for Oauth2. I am manually passing the authorization token/access token and its working fine. But we need to implement Oauth2 so that our user can authorize themselves and can generate reports. on clicking the authorize button our angular app is opening and showing token in the console. Only apply to this job if you have something familiar. 90% of the stuff is implemented all we need is help completing it. Wont take more than 30 minutes if you are an expert in this. Budget is $10. All the work will be done via teamviewer. Thanks.