You are providing wrong Database connection details. From the logs i see you are using Administrator. This is not a database user. This is Informatica Admin account. Please create a new DB schema if not done already and create RS again with correct DB connection details.
Also refer to the Installation and configuration document.
From the Session log, it's very clear that the connectivity to the database failed because of incorrect login credentials.
In tnsnames.ora file, I could see PCIS_REP. Is this the Service Name for the PowerCenter Repository database schema you created in Oracle?
If so, first, please check the database connectivity using sqlplus,
sqlplus username/password@<Service Name>
If this is thru then provide the same login credentials in the Repository Service while creating it.
If not, create (or get it created by DBA) a new DB schema for PowerCenter Repository and add an entry for it in the tnsnames.ora file, and test the connectivity outside and use it while Repository Service creation.
Here is the snippet from the session log you shared here.
It clearly says that you have used Informatica Admin user and the connect string you used was that of Domain Repository. You should use the username and password provided by the DBA for the DB schema of the PowerCenter Repository and the Connect string should be the Service Name in the tnsnames.ora file.