First installation screen hangs


I’m trying to install Piwix but I can’t even get past the first screen.
I click “Next” and then nothing happens.

After a while, it says this :
"Piwik encoutered an error: Maximum execution time of 30 seconds exceeded (which lead to: The mysql driver is not currently installed)"
Which is weird because mysql IS installed…

Any help, please?

Thanks in advance.