I installed a default install of OCP 4.1 on AWS using the installer at try.openshift.com.

I then created a new namespace, installed the CRW 1.1 Operator into it from OperatorHub, and created a new CheCluster using the default values.

The Postgres pod entered a CrashLoop reporting:

pg_ctl: another server might be running; trying to start server anyway
waiting for server to start....LOG:  redirecting log output to logging collector process
HINT:  Future log output will appear in directory "pg_log".
 done
server started
=> sourcing /usr/share/container-scripts/postgresql/start/set_passwords.sh ...
psql: FATAL:  role "postgres" does not exist

If I instead created a CheCluster using a Postgres 10 image:

     postgresImage: 'registry.access.redhat.com/rhscl/postgresql-10-rhel7:1-35'

And deleted the postgres-data pvc (since it contained Postgrs 9.6 data), then CRW successfully got installed (Postgres, Keycloak, Che)