Anyway, as far as I can tell we can just create the ocfa user manually. This is obviously for any psql implementation, and not OCFA specific.
1. Make sure the 'ocfa' user has been created in linux. If not, you might have bigger problems. Try installing OcfaArch again.
2. As root, login as user singlegres
su - singlegres
3. Login to psql
4. Create the 'ocfa' user
CREATE USER ocfa WITH PASSWORD 'password';
5. Allow the ocfa user to create databases
ALTER USER ocfa CREATEDB;
6. exit psql
Now the ocfa has been created, and is able to create new databases. You can test this by creating a case, or just go directly to pt.3 Ocfa Installation - dns, apache, and permissions
For more information on psql user administration try here.