"PHP's XML Extension is not loaded or available"

When initializing the database, there’s this column to the right saying there’s something wrong with the XML extension. The problem appears to be row 66 of onyx-rss.php. I’m using PHP 7.

Since I got your attention (hopefully), there’s another issue: The “continue” button in the initialization phase does not respond to my clicks. I’ve set up database and user correctly and it should have the correct permissions.

You might want to make sure that your php-devel is installed…
that provides the xml extensions