Debugging PHP over VirtualBox

My setup:
Host: Windows 10
Guest(VM): Ubuntu 18.04 with XAMPP

I work on the Windows 10 machine and edit my current project with PHPStorm. The project is mounted on the VM and is added to the httpd.conf. I have a bridged network so I can call the localhost of the VM over the machine's IP on my host system.

Now I would like to debug the code on the host system. Therefore I installed Xdebug on the machine and configured PHPStorm so it can work with a remote PHP interpreter (followed this guide).

I can run the code with the remote interpreter but I can't connect to Xdebug.
The error message in PHPStorm is: "Connection with 'Xdebug 2.6.0' was not established. Validate installation." -> " 'Xdebug 2.6.0' extension is installed. Check configuration options. Show phpinfo"

My php.ini

How could I debug my project?