File link redirects to home page

Trying to troubleshoot a WordPress issue for a client. Recently switched servers, migrating WP install with Duplicator plugin. Mostly smooth transition, but for some reason, links to download pdf files seem to redirect to homepage.

This should be the link for the file:
https://saint-vincent-church.org/wp-content/uploads/2015/02/Bulletin-2015-02-08.pdf

However, link on page gets generated as this:
https://saint-vincent-church.org/?download=%2F2015%2F02%2FBulletin-2015-02-08.pdf
… which then redirects to homepage.

Not sure if this is a theme issue, since it didn’t occur with our last host. I did disable all plugins to see if that was the problem, but still got the same result. I haven’t mucked with the .htaccess file. Possibly because our older host was running on a Windows server and now we’re on Dreamhost’s Linux servers? I don’t know enough to even determine whether that has anything to do with it.

Thanks in advance for your help.