Connection to JDE is at the database level. Such as iSeries (AS400) it is to the DB2 files (F0101, F4210, etc...) These are access via ODBC. You will need a user name and password at least on DB2.
On our Qlikview server "iSeries Access for Windows ODBC data source" is defined in the ODBC Data Source Administrator under System DSN. You will need Client Access basic install is you are on an iSeries. I believe that SQL database is already in Windows. Oracle DB I have no idea.