I had some small issues getting the insync client running on a fresh (defaults install) of Ubuntu 18.04

to install insync-nautilus

Unfortunately the standard Ubuntu 18.04 deb package doesn't add a list file for the insync repo so you can't enable nautilus integration until you create the repo list file

create a file /etc/apt/sources.list.d/insync.list file with the following content

deb http://apt.insynchq.com/ubuntu bionic non-free contrib

Then you can run
sudo apt-get install insync-nautilus

to get the notification icon

sudo apt-get install sni-qt

To get the files to sync

Click on the notification icon select Open App Window at which point I get an error insync.py "-" is ready. Then hover over the person icon and select Files and under the My Drive tab select all the files and right click and select the Sync Entire Folder and then click the default location of your insync folder.

Reduce log error messages

I had a heap of errors in the out.txt file which you can find by clicking the three dot menu choose Support the click LOCATE LOGS

Gtk-Message: 10:00:59.429: Failed to load module "canberra-gtk-module"
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiognutls.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiognutls.so
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiognomeproxy.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiognomeproxy.so
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so
Gtk-Message: 10:02:58.135: Failed to load module "canberra-gtk-module"
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiognutls.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiognutls.so
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiognomeproxy.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiognomeproxy.so
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so

I tried to fix them with

sudo apt-get install libcanberra-gtk-module:i386
sudo apt install libcanberra-gtk-module libcanberra-gtk3-module

They are not totally eliminated but reduced:

'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiognutls.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiognutls.so
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiognomeproxy.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiognomeproxy.so
'g_io_module_load': /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so: undefined symbol: g_io_module_load
Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so