32bits UID have nothing to do with the number of bits of your CPU. Historically, Unix commonly use a UID max value of 65535 (16bits UID). Now most recent Unix and Linux OS are supporting 32bits UID (so up to 4294967295), so services like LDAP or Winbind could be fully supported.
A quick search seems to indicate that you can configure the UID limit in /etc/login.defs, I must admit I don't have my Linux VM on hands so I can't check this is relevant to CentOS or not.
Edit: Just seen your update. Seems weird. Can you please indicate what version of DirectControl you are using? You can see that by running "adinfo -v". I suspect the version you are using may not support CentOS 7
Hope that helps
Fab