The package app-emulation/phpvirtualbox is not really an emulator but rather an web interface to control and manage app-emulation/virtualbox. As such, it should be in category www-apps instead. An additional point is that the ebuild inherits the "webapp" eclass. Sidenote: I do have an updated ebuild (EAPI 7 instead of 6) that uses git sources instead of an actual release here: https://github.com/kripton/kripton-overlay/blob/master/www-apps/phpvirtualbox/phpvirtualbox-6.1.0.9999.ebuild