I was also able to successfully install the drivers using the method by @itpropmn07 with one slight change.
mokutil --import did not work on my ASUS motherboard so I had to import the key from inside the UEFI interface.
This can be done by loading the .der file onto a USB drive and navigating to the Secure Boot > Key Management section and selecting the Append Default db option.
A popup will then ask if you want to append the system default db. Make sure to select No, which will then let you browse to your file on the USB drive. Choose key certificate blob as the selected file type. Finally, save and exit.
You can verify that the import was successful by running:
Note: it would be wise to backup your secure boot keys and have them stored somewhere safe in case something goes wrong. Use the 'Save Secure Boot Keys' option for that. When restoring the keys, use UEFI secure variable as the file type.