Hi,
No choice here, definitely Oracle database.
The embedded database (EnterpriseDB PostgreSQL I think) is installed on the same folder than the Capital installation, use the same hardware resources than Capital, and same "Storage drive". I don't know if we can install it on a different server.
But if you look at the system requirement, with your enterprise type and architecture, this can lead your decision.
As per this System requirement, there's a note about the embedded db.
Best Regards