Usually DB's have their own auth domain defined in SAS i.e. you will need an ID that is created in the database and can authenticate against it. It can be of same name that's not an issue, however the password could differ. You can check with your DBA about it.
It's always better to try and connect from outside of SAS using DB client to confirm as well.
Whenever one is accessing any table in an external database, the password defined in the external database However if the external table is defined as a table in the metadata server then the database password would exist in the metadata server . Then you may not need the password. There could be exceptions,
The SAS Administrator (and DBA) would be the first first person to reach out..