The pic above means, please translate the dialogue.
By the way I forgot the header: "Dateien einfügen" (It should be plural because we can insert a lot of files in one step).
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The way to choose files for upload, is not really clear at this point of user-dialogue! The button tells to make something, what can't be done in the next step. The button should tell the user, that he will open the interface for choosing the files. So he should tell: "Select files" - in German "Dateien wählen" (plural because...)
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