My Win 10 install was only 5 days old, and since I hadn't logged in as admin yet, there was no admin profile created (thus no Startup folder existed for the admin user). The things you learn!
Still, this is something to be aware of in future: your users may be trying your software on a new user profile, which can cause it to fail or return unexpected results. Now I have to amend all my sources to handle such missing profiles; so not a lost cause by posting about it after all.
