- Pester them to release a properly signed driver - good luck!
- Switch Windows into a mode so that it allows the install of unsigned drivers. Lots of info out there about the handful of different ways of doing that. For instance…
https://windowsreport.com/driver-signature-enforcement-windows-10/
From all accounts the switching boot mode method is the most reliable.
All of them are hacks for the real problem though, the drivers should be signed!