The WordPress installer has been updated in such a way that it's now possible to fill out the installation panel ... but it installs a Maria DB.
Ah, now I checked with FTP. It has in fact created a WordPress installation, but all the notifications etc that get sent to the user refer to Maria DB. e.g. "MariaDB user 'newapp' has been created." (when I was creating a WP installation called "newapp")
And they are listed as Maria DB databases
A WP app can take a minute or two to install.
Once everything is finished you should get a notification saying that the app installation is complete.
OK. My bad. I'm out of my depth here, as I'm not really a dev. I now realise that Maria DB is a dropin replacement for mysql, so you've probably taken the decision to use that rather than mysql.