To allow managers of managers to access review cycles of their indirect reports (their direct report's direct reports), the Admin should follow the steps below:
Step 1: Navigate to the "Admin Panel" found on the top navigation bar
Step 2: Click on the "People" tab found on the left Administration panel
Step 3: Under the "Permissions" tab, check "Review cycles of indirect reports"
Once you've enabled top down visibility in reviews, your managers of managers will be able to access the reviews of their report's reports by going to that person's "You" page and clicking into the review under the "Reviews" section.
If you get a screen with no response, it is because the person has not received a review yet.