Log in to the RDS Oracle Server from the master user account (created during RDS Oracle instance creation) and execute following commands:

create user $rangerdbuser identified by “password”;
GRANT CREATE SESSION,CREATE PROCEDURE,CREATE TABLE,CREATE VIEW,CREATE SEQUENCE,CREATE PUBLIC SYNONYM,CREATE ANY SYNONYM,CREATE TRIGGER,UNLIMITED Tablespace TO $rangerdbuser;
create tablespace $rangerdb datafile size 10M autoextend on;
alter user $rangerdbuser DEFAULT Tablespace $rangerdb;

Where $rangerdb is a actual Ranger database name (for example: ranger) and $rangerdbuser is Ranger database username (for example: rangeradmin).

If you are using Ranger KMS, execute the following commands:

create user $rangerdbuser identified by “password”;
GRANT CREATE SESSION,CREATE PROCEDURE,CREATE TABLE,CREATE VIEW,CREATE SEQUENCE,CREATE PUBLIC SYNONYM,CREATE ANY SYNONYM,CREATE TRIGGER,UNLIMITED Tablespace TO $rangerkmsuser;
create tablespace $rangerkmsdb datafile size 10M autoextend on;
alter user $rangerkmsuser DEFAULT Tablespace $rangerkmsdb;

Where $rangerkmsdb is a actual Ranger database name (for example: rangerkms) and $rangerkmsuser is Ranger database username (for example: rangerkms).