db can't be dumped

[lorenzobattelli]

dear all, I've got problems in dumping my db: php7.3, Laravel 6.x, here's the error message:

sh: mysqldump: command not found
Database 'Tirocinio' cannot be dumped

after running the command
php artisan backup:mysql-dump

I've followed the previous steps as tutorial says

may it be a matter of Laravel version? mine is 6.X, while tutorial says that it work in Laravel 8...
New version 4.* works with laravel 8
which version should I downgrade at?