I have a folder on my laptop (Ubuntu Mate 16.04.3 LTS), and one on my desktop machine (Kubuntu 14.04.5 LTS), that I wish to sync, and because the laptop may be on any of several wifi connections (home, Starbuck's, my game shop, etc.) at a given time, I need to sync via a cloud service, but the folder I need to sync is too large for my Dropbox (I can pay for more Dropbox storage, but I'd prefer not to).
I've obtained sufficient space on Google Drive, and I have google-drive-ocamlfuse installed and confirmed working on both computers. Unfortunately, google-drive-ocamlfuse doesn't sync local folders as the Dropbox app does; instead, it just makes the cloud folder look like a local folder, and access through the Internet is too slow to use directly for loading a large program (like a game).
I've installed Unison on both machines and created local folders to sync into, but it turns out only to operate when I open the software, wait for a protracted scan, and then click "Go" to complete the operation (and it doesn't seem to do that at all well; multiple attempts still had files in the cloud that wouldn't sync to my desktop machine).
How can I set up continuous bidirectional sync between two arbitary folders -- to work like Dropbox, that is? Software that will sync two local folders, or a local folder and a network storage, ought to work, because google-drive-ocamlfuse makes the cloud storage look like a local folder. I'd prefer a free or free and open solution for this, if possible.