Typically a itgenboe313 indicates that the download client disconnected, but the numbers seem strange.
Increase Time-out
You might want to extend the timeout as described in Avoid timeout error on Power BI OData download.
Test using Curl
To factor out Qlik as a cause, please try to run the download using curl as described in:
Possibly related: Germany
But given the German text and 7 minutes on a single API call from Postman to Exact Online it may also relate to a seemingly common problem in Exact Online Germany environments, where time-outs occur. You might want to check the screen Session I/Os for response times of API calls. They should all be below 10 seconds, and typically way below 1 second for this specific table.
In case there are larger response times, it is recommended to reach out to Exact Online Support. Their formal stance is that there are no guarantees on response times on the API, but in practice they also know that when such problems occur ultimately the customer will leave the Exact platform.