Try with FastSCP or with datastore browser
Well it worked from the beginning with the datastore browser, but I needed a solution which can be automated. It does not help if I have to remember to copy every day.
But, big suprise, it works flawlessly with Veeam FastSCP!
It's a bit more complicated as I can't put everything into one script (->respectively, that I have to schedule the two tasks, backup and copy of the backup so they won't overlap). But hey, as long as it works somehow I won't complain.
Many thanks for the help