Well, you need to install keys for the sources. But this kind of support is beyond Hestia, and you might need to pay for help. 
Best advice is still to call Hetzner supprot. They have likely screwed up something with their install images.
Well, you need to install keys for the sources. But this kind of support is beyond Hestia, and you might need to pay for help.
Best advice is still to call Hetzner supprot. They have likely screwed up something with their install images.