Paid file download not working

When I upload the pdf file to be downloaded through the product page, then the customers version of the file is corrupted. When I upload the file directly to the safe folder and linked it to the product, then the customer gets an 403 forbidden error. I have tried to update to version 2.0, but I still have the problem. Strangely I don't have any problem with free downloads.
I can't seem to find any similair topics on this, though the error is briefly mentioned in the changelog of 2.0.

Hi,

Have you tried with the same file as free and paid file ?
You maybe have the wrong access for the folder where the files are uploaded, be sure that the permissions are set to 755. (by FTP)