Its a looong time since I installed Oracle8i, but...
Out of the box you should have a user SYS password CHANGE_ON_INSTALL, and a user SYSTEM password MANAGER.
I seem to recall that when creating the database you are offered the option of installing the SCOTT/TIGER user and schema, but it is a choice not a default (but I may have misremembered this).
To help us diagnose your problem:
Check that your database and listener are started. See
https://coderanch.com/t/81066/Oracle-OAS/getting-error-ORA-TNS-no Can you connect to the database using SQL*Plus as SYSTEM/MANAGER ?
Can you connect to the database in SQL*Plus as SCOTT/TIGER ?
If you can connect as system and not as scott then it is advisable to create a user and schema to own the database tables and code in your application.
Issue the command
CREATE USER <app_owner> IDENTIFIED BY <password>;
GRANT CONNECT TO <app_owner>;
Try to connect usin jdbc.
If you get an error please post the stack trace here. If there are ORA- or TNS- error number please be sure to include them.