Call the company you ordered from and ask them to reship the order because your package was stolen. Also ask if for a signature to be required upon delivery so you can be the only one to receive the package. This kind of thing probably happens all the time and they should be willing to help you out.

It always amazes me that in the US they just leave your packages outside like that.

Well they certainly do that in other countries as well.
As for germany though you actually have to do some paperwork (of course, nothing can be done without filling out paperwork after all) and then they will drop the Package at the spot you actually chose for your delivery. Say for example the shed in your garden.

For something like that, the company should be requiring signature-on-delivery as standard. I'd definitely get in touch with them to see if they can send a new one, this time specifying /not/ to just leave it at the door.

Wait the leave package at the door? What kind of horrible service are you using?

American service. 😒

Now that's what I call a sticky situation!