Error trying to open grav

When I run “php - f index.php” from /var/www/grav/grav-admin I get no response - just a return to the prompt.

When I run “/bin/grav server” from /var/www/grav/grav-admin I get “Grav Web Server” in a brown font then “sh: 1: exec symfony: not found” followed (in a green box) by “[OK] Built-in PHP web server listening on http://127.0.0.1:8000 (PHP v7.4.33)” then nothing. (I was able ctrl-c and return to the prompt.)

Do I need to do this as described here https://getgrav.org/blog/using-builtin-webserver?

wget https://get.symfony.com/cli/installer -O - | bash

Follow the same steps as above to symlink; on my test Raspberry Pi machine, I used:

sudo ln -s ~/.symfony/bin/symfony /usr/local/bin/symfony