The Shapespark scenes are located in the Documents\Shapespark folder by default. This can be changed as described in Change default folder location - #2 by jan To transfer a scene between computers you need to transfer its folder.
You could potentially use a folder which is synced automatically with the cloud (eg. a Dropbox folder) to keep scenes. However, it’s very important not to modify a shared scene folder from two computers at the same time because it will lead to scene corruption.