How to get Authorized Client Ad accounts lists

[Tarannum]

Other Client authorize OAuth2 via Google Sign-in with scope=https://www.googleapis.com/auth/adwords.

After Authorization I want to get the Authorized Client's Ad accounts.

But I am getting error message "The caller don't have permission". 

Can anyone help me what more need to be included in scope or the way to get the Client's Ad account after authorization.

hit url - https://accounts.google.com/o/oauth2/v2/auth?

 scope=https://www.googleapis.com/auth/adwords&

 access_type=offline&

 include_granted_scopes=true&

 state=state_parameter_passthrough_value&

 redirect_uri=https://example.com&

 response_type=code&

 client_id=client_id(value)

Please help. Its urgent.