The strange part is, a few months ago, this would application work fine without any issue. Now I get this error.
I'd contact the application developer and make sure this is a legit mistake. Drivers that are all the sudden untrusted are a dead giveaway for malware, specifically rootkits.
If it is a legit mistake, you can reboot and hit F8 while Windows is loading up. There is an option to disable the Integrity Check that will then allow installs of unsigned drivers.