To install Thunderbird client, open a terminal window and enter the following command:$ sudo dnf install thunderbird <enter> To get the calendar working in Thunderbird, add the Lightning addon from Extensions in Thunderbird.
To synchronize Google Calendar with Thunderbird Lightning, open Thunderbird and install an add-on named "Provider for Google Calendar" by Philipp Kewisch. Follow the instructions after the install to grant permissions to your Google Calendar and synchronize.
Lightning Calendar comes with Thunderbird on Ubuntu 18.10. To enable it, open a terminal window and install the following package: $ sudo apt-get install xul-ext-lightning <enter>