It looks like you are saying the it works using the secret? (It should, just want to make sure).
If that is what you are using, then run the cronjob every minute.
The curl and wget commands talk to phpList via the web interface, and that has changed lately, and you might need more than just a command: you need to be logged in before you can run commands like that, and the system wants to see a cookie and/or session id token before they work. This is the main idea of the secret in your last command.
For the command line argument, /usr/bin/php …, if you are using a hosted computer, then you’ll need to know what the full path to the php or php-cli command is, and your webserver. It’s tricky, best to ask your hosting provider to save trial and error time.