Hi Mog51,
What version of Mac OS are you trying to instal the Silab v6.0 Driver on to? Anything prior to Big Sur (Mac OS 11.0) uses a system called a kext (Kernel Extension) to implement device drivers. So Mac OS Catalina (10.15.x) and prior versions of Mac OS all use this kext system. Silab v 5.3.5 is a kext.
For reasons of security, Big Sur does not allow kexts and instead Apple developed a system called Driver Extensions to implement Drivers such as Silab. Device driver providers have had to rewrite their software to work with this new system. That is what Silab v 6 is. So, likely, v 6 will only work with Big Sur and newer - for anything earlier use v 5.3.5. This is also why Catalina used to issue a warning dialogue box letting you know that the version of the Silab kext that you are running would not be compatible with future versions of Mac OS.
I hope this helps. Cheers mfed
Thank you all for your responses!