As the file recipient, you may or may not have permission to download a file that was sent to you, depending on whether the file owner has allowed downloading.
To find out if the file owner has allowed downloading, look for the download icon in the top-right corner of the file viewer.
If the download icon is enabled, the file owner has allowed you to download the file.
If the download icon is disabled, the file owner has not allowed you to download the file. Please contact the file owner directly if you need to download the file.