VirtualBox is a useful Open Source virtualization tool for enterprise and home applications. Last time I had a problem: Kernel driver was not installed (rc=-1908)
step.1. install
dnf install elfutils-libelf-devel.x86_64 kernel-devel kernel-devel-4.18.11-200.fc28.x86_64
step.2. run as root
/sbin/vboxconfig