The additional software "Sony Reader for PC / MAC", with which protected eBooks are to be transferred to a Sony eReader, is no longer compatible with the common DRM standards. Therefore you can no longer open protected eBooks with this software.
We do not have informations about support from Sony for their own eBook-Readers. See an example here: http://sony-eur-eu-de-web--eur.custhelp.com/app/answers/detail/a_id/138808
The software Adobe Digital Editions ADE does not recognize the Sony eReader, which is why it can not be used for a transfer.
With a little a detour via ADE, a transfer can still be made:
- Install Adobe Digital Editions and authorize it with your Adobe ID as described here.
- Install Sony Reader for PC and authorize both the Sony Reader for PC software and your Sony eReader with your Adobe ID.
- All three (ADE, Sony Reader for PC and eReader) should now be authorized to the same Adobe ID.
- Download an eBook and open it with Adobe Digital Editions.
- Now open Sony Reader for PC and select "File" → "Import files". A new window opens. Navigate to the Adobe Digital Editions folder: "PC → Documents → My Digital Editions." Select the eBook you have borrowed and downloaded to ADE.
- The eBook will be imported into Reader for PC.
- Connect your Sony to your PC.
- From "My Library" in Reader for PC/Mac, select the eBook you'd like to transfer and click the bottom-left button.
- The eBook has been successfully transferred to your eReader. You can now disconnect the eReader from your PC.