iCloud Drive - Stop Automatic File Upload & Download

Read through the various issues described against this 3rd-party tool:

https://github.com/Obbut/iCloud-Control/issues

-esp-

https://github.com/Obbut/iCloud-Control/issues/39

https://github.com/Obbut/iCloud-Control/issues/36

https://github.com/Obbut/iCloud-Control/issues/23

They make interesting reading re how to manage iCloud. But it does seem that you cannot simply not download a file, the best you can do is evict it once it has been downloaded.