Archive template not working for custom post type

Your problem was the & which WordPress cannot support as is. That is because & is used as part of a URL to join query vars together. Like this:

example.com/file.php?foo=bar&baz=zoo

Also, as pointed out in comments file names have to follow the naming standard. Which is clearly laid out in the documentation.

The format is archive-[slug].php

That’s why when you renamed the file it started working.