I am on Linux and the directory /home/xy/JoplinBackup doesn't exist. There is a directory /home/xy/.config/joplin-desktop/JoplinBackup that only contains a directory profile and a file all_notebooks.jex, both from Dez. 18, 2022.
Do you mean that I need the plugin? I had understood that Laurent’s statement "By default, Joplin saves at regular interval your notes" means that Joplin makes a backup without a plugin.
The Backup plugin is built in, so unless you have disabled it on purpose, it should be enabled and working by default. I think a screenshot of your installed plugins from the Joplin settings, and a screenshot of the Backup plugin's configuration would be helpful here.
Yes, the plugin is pre-installed and uses some default settings you can tweak. Look under "Option" -> "Plugins"; you should find it there.
For instance, I prefer backing up all notebooks individually instead of the pre-configured setting as "one big JEX file" ...