When activating your computer which is part of your organization you receive an error 0xC004C020 which says "The activation server reported that the Multiple Activation Key has exceeded its limit", the chances are that you need a new key. The organization uses what is called MAK or Multiple Activation keys to activate multiple computers with the same key.

It is possible that your PC was formatted, and you have lost your previous key or when the admin gave you the key to activate, it already had exceeded the limit on the number of activation.

You should call in your System admin to get this resolved. And if you are the system admin, and believe that the limit didn't cross, you can call Microsoft support to get this resolved.