->hideFromIndex()

app/Models/LibraryItem.php

@@ -78,7 +78,7 @@ class LibraryItem extends Model implements HasMedia, Sortable
              ->singleFile()
              ->useFallbackUrl(asset('img/einundzwanzig.png'));
         $this->addMediaCollection('single_file')
-             ->acceptsMimeTypes(['application/pdf'])
+             ->acceptsMimeTypes(['application/pdf', 'application/zip', 'application/octet-stream', 'application/x-zip-compressed', 'multipart/x-zip'])
              ->singleFile();
         $this->addMediaCollection('images')
              ->useFallbackUrl(asset('img/einundzwanzig.png'));

app/Nova/LibraryItem.php

@@ -104,15 +104,17 @@ class LibraryItem extends Resource
                        ->exceptOnForms(),
 
             Images::make(__('Main picture'), 'main')
-                  ->conversionOnIndexView('thumb')->showStatistics(),
+                  ->conversionOnIndexView('thumb')
+                  ->showStatistics(),
 
             Images::make(__('Images'), 'images')
                   ->conversionOnIndexView('thumb')
                   ->help('Upload images here to insert them later in the Markdown Description. But you have to save before.')
-                  ->hideFromIndex()->showStatistics(),
+                  ->hideFromIndex()
+                  ->showStatistics(),
 
             Files::make(__('Downloadable File'), 'single_file')
-                 ->help('Für neue Datei-Typen bitte bei den Admins melden. (Derzeit: PDF)'),
+                 ->help(__('Please contact the admins for new file types, otherwise pack the files in a ZIP! (Currently: PDF, ZIP)')),
 
             Select::make(__('Language Code'), 'language_code')
                   ->options(