Hi William,
You can find the answers below:
1. Do I need to set any scope value?
You need to put the value as public.
2. Do I need to set any redirect URI or not?
Redirect URI can be the base URL of Doorkeeper.
3. Do I need select the Confidential value or not?
Can you elaborate on this?
4. Are “authorize endpoint”, “Access token endpoint”, and “Get user info endpoint” using doorkeeper default route, right?
Yes. The default routes should be used.