This is due to the service systemd-networkd-wait-online being disabled.
Enable the service like so:
sudo systemctl enable systemd-networkd-wait-online
This should execute without errors.
After that reboot your system. Your network share should mount at boot now.
If the share is still not mounting, check:
systemctl status networkd-dispatcher.service systemd-networkd.service
And see if either service is disabled and enable them too. Then reboot your system.