Sorry looks like someone accidentally moved you out of the MOSC communities and into the OTN communities. Please re-post this question in the Exadata General (MOSC) community.
Did you check the schematic file ?
I think you can manully change the Rack name on the review page.
Also check if all the steps are performed correctly: EM13c: Cookbook for Discovering Exadata in EM Cloud Control 13c (Doc ID 2371835.1)