Kernel driver not installed (rc=-1908) when running Windows 10 VM
After struggling with the same issue all night I finally found a way to keep Secure Boot enabled & got Virtualbox VMs running properly- in Ubuntu Xenial (16.04.3).
I used ppa:costamagnagianfranco/virtualbox-ppa. Though maybe another one would work - possibly even the official one - I didn't try.
A key part of the process was signing the kernel module, and these instructions worked for me.