If you add your Google account in 'Settings > Online Accounts' then, in the file manager sidebar right at the bottom, click 'Other Locations' and your Google Drive should be listed there under the 'Networks' heading as '<yourname>@gmail.com'.

[DISCLAIMER: I'm 99% sure that was all that was involved. But I set up that Linux box quite a while back. So apologies if I've forgotten a step and am misleading people!]