These transactions will appear as cash ledger transactions (Kassendaten) in your cash ledger (Kassenbuch) on DATEV Unternehmen online (DUO). From DUO you can then export the cash ledger transactions to DATEV-Rechnungswesen-Programme.
The transactions attachments are stored on Belege Online in a folder located at "Buchführung/IMPORT YYYY Kasse/dd Month" (e.g. Buchführung/IMPORT 2021 Kasse/12 Dezember) and linked to the related transaction.
More information about the data transfer process of transactions and attachments imported via DATEV XML-Schnittstelle online are available on DATEV Help Centre: DATEV XML-Schnittstelle online - Ablauf der Rechnungs- und Kassendatenübertragung