The app "Der Ordersatz" does not read any private data from your Phone/Tablet!
The app needs access to your camera to scan barcodes. The photos provided to the app are scanned for a readable QR code/barcode directly in the device. There is no transfer of image data.
For technical reasons, the app "Der Ordersatz" requires access to your "Phone" function in order to check the current online status ("Internet reachable"). However, the app does do not access your contacts, does do not access your e-Mails and does do not read other personal data.