If you want to get Your Domain Registration AUTH CODE for a domain name that is currently registered through RegisterClub.com (via the REGISTRAR, ENOM), you will need to make sure that your domain is paid in full, and current (not expired).
If the domain is paid in full, and current (not expired), then you will need to follow the following instructions:

To get the domain AUTH CODE, simply contact support and request that RegisterClub.com send the AUTH CODE to the Registrant/Default Contact ADDRESS on file in the WHOIS DATABASE.

If you have any further questions, please feel free to contact support.