I know that everyone has been waiting a long time for sync and I want to reassure you that it is high on our list of priorities. As users of Squid ourselves, it’s something we really want as well! We appreciate your patience.
This is something we’ve been investigating since the app’s inception and we continue to investigate constantly. Syncing is a very difficult problem to solve, especially with regards to handwritten notes which can be combined with images and text and contain backgrounds from multiple PDFs. I don’t have an ETA for when sync will be supported, but rest assured this is a high priority for us. We appreciate everyone’s feedback on this idea.Michael commented
Just subscribed to premium, and surprised to find this still hasn't been implemented. A rough workaround, for those that would like same ability to synchronise between devices, is to manually change the "Device name" within the Backup and Restore settings to be the same for both devices. I've used "google Combined Devices" on my phone and Chromebook, so both devices will look into the same linked Dropbox account for backup. Backup from one device, then restore on the other device.