If you don't have the PDI (Pre-Delivery Inspection) document yet, you absolutely need to download it now. Here's a post from @KentuckyKen where he provides the PDI document.What are these plugs I keep reading about and how to check them?
The four rubber plugs that came in a bag with your Clarity from Honda go into 4 oval holes in the underbody. The holes were used to secure the car during shipment. The PDI document shows where they belong. If your dealer didn't install them, tell your dealer to get them and install them or give them to you so you can install them.