Permission denied on file upload with IIS

Hi all, I'm hosting an application on IIS and am having an issue with my file uploads. When I upload the file, I get the following error: fopen(D:\IIS\server-name\wwwrootapp-name\public): failed to open stream: Permission denied

This seems weird, because the physical path for my application in IIS is the public folder and the rest of the application displays correctly.

I'm not sure what causes this issue. I have given full 'Modify' permission to IUSR, and have a working symbolic link from my 'public' folder to 'storage/app/public'

Here is the line dealing with file storage:

$filename = $request->documents[$i]->storeAs('docs', $request->documents[$i]->getClientOriginalName(), 'public');

In addition, I have no problem writing log/view files in storage, so it seems the issue is with the public folder. If anyone has any experience with this issue I'd be happy to hear it. Thank you!