From your post I think I am doing what you ask-
My Desktop computer runs LR-Classic v7.3.1,
I make Collections that I sync to the Cloud (these are Smart Previews)
I run Lightroom-CC v1.3 on my laptop and it shows me the photos from the Collections.
I have a choice in the Lightroom-CC preferences to Download the Smart Previews, or not at all.
LR-Classic will only sync Smart Previews (Not originals in the Desktop) to the Cloud.
LR-Classic will only sync files you place in Collections (not necessarily the entire Library!)
My option is 'on' to download the Smart Previews to my laptop for faster viewing:
I already have that same setup already, but I want something similar to CC where my laptop is able to download the Smart Previews only.
When I turn on the sync function in Classic it starts downloading the full originals, and it doesn't give me an option to download smart previews only..
If I understand what you ask-
With LR-Classic (desktop) you can only sync Smart Previews UP to the 'Cloud'. You cannot sync them DOWN to use with another Classic installation (Laptop). (but you can with Lightroom-CC on the laptop!)
To Classic-edit only with SPs on the laptop you would need to "Export as a Catalog- with SPs" from the desktop and copy this catalog to the laptop.
When I turn on the sync function in Classic
Where is this? Desktop or Laptop? You can only sync one Classic catalog to the cloud and that would normally be the desktop.
exactly same problem here, please let me kno if you can figure it out.