Check permissions for the file. There is a Sharing option in Drive that allows creators to disable options to download a file.

File and folder management in Google Drive on the web is pretty straightforward. Hover over files and folders to see options ...

You can easily share files on Google Drive with just a few clicks, and specify who can view, comment, or edit files.

To help secure your Google Drive, use two-factor authentication and be careful when giving other apps permission to use your Drive.