The steps leading to the error have users creating the referenced /opt/CA/CABI/postgres directory. After creating the directory the instructions call for a recursive chmod command to set permissions to 777.
Once that is completed the postgres DB is created. During the DB creation it creates the /opt/CA/CABI/postgres/data directory and all necessary files and sub-directories that reside under it.
During the DB creation process the permissions assigned to all files and sub-directories that reside under the /opt/CA/CABI/postgres/data directory are 700.
If the recursive chmod to 777 is run against the /opt/CA/CABI/postgres directory after the postgres DB is created it will result in incorrect permissions and failed DB start up.