For later versions of Ubuntu (17.10 and above) on GNOME, you might observe that the Insync icon or GUI does not show up. This is caused by the update to GNOME and you'll need to install the AppIndicator extension for this.
To install, click here or just run the following commands:
sudo apt-get update
sudo apt-get install gnome-shell-extension-appindicator
Then, follow the Setup Guide as usual.
If you're on GNOME, install the AppIndicator extension found here. If you're using Xfce4, right-click the tray icon and disable
Status Notifier Plugin.
In case you’re still having trouble, feel free to reach out to firstname.lastname@example.org.