@VinodBavandlaI think you have it correct, with some special attention to the TransactionModule.
CDM is an account based model, which means that your Customer (from your EDM) indeed is an Account (CDM) and can be an organization or a natural person.
The Account (your EDM) is indeed the ServiceAccount (CDM)
If you are not interested in how your full transaction has been set-up (with all parties involved), you can use Transaction (CDM). This as the transactions are generally handled within an ERP system and you only need to get some details from it for your use-case)
Just adding to it Transaction module sed to describe a transfer of money between parties. The transaction module includes the debit and credit parties and all intermediary agents who are involved in completing the transaction. Just to hold debit/credit transactions, Transaction is the entity you could use