This lady has a nifty solution to your query: http://www.alicekeeler.com/teachertech/2014/12/10/google-docs-force-students-to-make-a-copy/
Ensure also that the document is visible to anyone who has the link. You may do this by clicking on the Get link icon (the icon which looks like a paper clip on the upper right-hand of the panel when you click once a doc in Google Drive), then the Sharing settings link, then the Get shareable link icon. Afterwards, change the document's accessibility to "Anyone with the link can view/edit/comment" (whichever suits your preference, though I prefer the view or comment option so that the collaborators cannot edit the original template directly).
The same lady also suggested in a similar outdated blog that, for convenience in sharing the link, it would be better to use a URL shortener (such as https://goo.gl) for the whole link to the document clone (i.e., including the appended /copy at the end of the URL)
I tried her suggestion and it works!