The best software for e-book management in Windows, Linux and macOS it's Calibre. It can handle a variety of devices, including Kobo.
Written in Python 2.7, it's updated quite often.
In the help section of the website there is a FAQ for Kobo devices, if something doesn't work as expected.
The installation of Calibre it's easy: from the download page, copy the shell commands, and run them in a Terminal. It uses "sudo" from your user login. If you don't use "sudo", switch to root, remove the "sudo" command from the shell commands and re-run the commands.
The shell commands will download the install script.
The script will install Calibre in /opt/Calibre. Start the program from the menu of your desktop environment. A small wizard will help you to configure Calibre for the first time.