While VirtualBox is available in RPMFusion, it is recommended to use libvirt, which is already built into the kernel and the various virt-* packages can be installed as needed to get a hypervisor rolling. GNOME Boxes provides the functionality out-of-the-box with a Fedora Workstation install.

“Failed to start Load Kernel Modules” after uninstalling

If journalctl shows that you still get could not insert vboxdrv errors, run dracut -v -f then restart your computer.

Kernel modules do not build upon kernel update

Per the RPMFusion FAQ, run akmods-shutdown then load the modules and restart the service.

/sbin/modprobe -r -b vboxnetflt
/sbin/modprobe -r -b vboxnetadp
/sbin/modprobe -r -b vboxdrv
/sbin/modprobe -r -b vboxpci
/sbin/modprobe -r -b vboxdrv

systemctl restart systemd-modules-load

While RPMFusion doesn’t officially support VirtualBox with SELinux enabled, it is a terrible idea to disable SELinux.