Cannot view or edit default anti-spam policies. The link to other custom anti-spam policies is also not present.

You are probably not logged in as super administrator ('admin' account) and your administrator's account does not have permissions to view and edit anti-spam policy.

You need to log as 'admin' (or contact the responsible person if needed) and for the 'Mail Policies Administrator' Role for your account, set 'Manage Spam Policies: All ' permission.