Don't understand in what linking to a random collection would be better than creating your own. Especially a huge one with a lot of extension not conceived / working for mobile.
I feel like author should have explained how to do your own collection and how to add it. Only afterward pointing out you could add a collection from someone else and suggest some lists would have been nice.
As far as I know there is no limit on the number of devices you can sync. So yes it is possible to sync a folder on multiple devices and not only 2.