Hi René,
I don't speak German, so hopefully, English is okay. I had to use a translation feature, so hopefully, I understood correctly; Apologies in advance if not. If you search for A2 or A0 you should be able to find templates for these sizes in the app. After you create your poster/design there is an option to save as PDF. This should be all the printer needs, you shouldn't need anything outside the file itself. The only other consideration I can think of would be dimensions for printing, usually printing is done at 300dpi, so just ensure the file is large enough dimensions for getting a quality print, like 4961 x 7016 for A2 for printing. Hope that helps, Dave DB
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