This links to a webpage, Google’s PDF viewer, not the PDF itself. That’s why this is failing.
If you can, get the Web Content View link from Google Drive, not the Share Link.
What you need should be formatted something like this:
https://drive.google.com/uc?id=15v-w-xfrWF3X_EZ7iMYW9NRfOYELT2q7&export=download
If you can’t get this then you can extract the file ID from the link you do have then generate the link:
https://drive.google.com/uc?id=<fileID>