Problems with Admin console
If your Google Account is a Google Apps for Work account, by default the Custom Search service is disabled. If you have administrator privileges for your Google Apps account, you can enable the Custom Search Engine service by turning the service on in your Admin console. If the Custom Search Engine service isn't available in your account, try adding the service to your Google Apps account.
If you don't have administrator privileges, contact someone in your organization who does, and they can do this for you.
If you see the error "Invalid email address," when adding a user as an admin for a search engine, make sure the user has a valid Google Account. If they don't, follow the instructions to create one and try adding them again.