Do not install it. A cracked housing will leak under pressure and can fail completely.
If any part is cracked or broken, you should not proceed with the installation.
Your next step is to contact APEC or your distributor directly. They will arrange for an exchange of the damaged part. Have your order information ready.
While you wait for the replacement, you can unpack and familiarize yourself with the rest of the system. Lay out all the other parts—the RO head, tank, faucet, installation kit with tubing and fittings—to ensure nothing else is missing or damaged.
Installing a compromised part will lead to water damage and is not covered under warranty. It's frustrating, but it's much easier to fix now before everything is hooked up under your sink.