Buchungsdatenservice
Expenses achieve the status approved and are visible under Export. They are then transferred to DATEV by manual export or by automatic transfer as follows:
The receipt images are transferred to DATEV Unternehmen Online and you can also view them there if required under Applications-> Receipts -> Receipts and then in the receipt file under Spesenfuchs.

The booking data is sent to the DATEV data center. To read the booking data in Kanzlei Rechnungswesen, select “Bestand”, “Daten holen” and then “Mandant ergänzen”.

Then activate “Beleg-/ Buchungsstapel und Stammdaten (RZ)” and click on Daten holen.

When this process is complete, select Import in the menu Bestand and then Stapelverarbeitung.

You will then see the stacks and can process them:

You can find a document from DATEV on this topic here.
DATEV Rechnungsdatenservice 1.0
Expenses reach the status Approved and are then visible under Export. They are transferred to DATEV either via a manual export or through automatic transmission as follows:
The receipt images and receipt data are transferred to DATEV Unternehmen Online, where you can view and edit them.
You can also check the processing status in the Spesenfuchs log under Export → Download.

The import log in DATEV Unternehmen Online also provides information about the processing status.
Further information can be found here:
https://apps.datev.de/help-center/documents/1022872
Your tax advisor can then import the data sent by Spesenfuchs to DATEV into their DATEV accounting software.
The procedure is described here:
https://apps.datev.de/help-center/documents/1071255