Thanks. Looks like the new one is in the wrong place. Let's do the corrections one at a time.
Typing in Terminal is very exacting, most mistakes provide no warnings. I will type the commands that will unload the extension old in the correct location. Then we will tackle moving the new one to the correct location.
In case you'd like to review the commands, here's a
link that explains them.
First, be aware that I cannot actually issue the following Terminal command since I don't have any file in the /Library/Extensions/ location, on this Mac, that I can 'mess' with. Use the following at your own discretion. Even wait for confirmation from others here.
Here is the Terminal command that should unload the old SiLab driver:
sudo kextunload /System/Library/Extensions/SiLabsUSBDriver.kext Double-check the text in blue. The "sudo" part tells Terminal that you have temporary permissions to make changes. The rest of the text tells the System exactly what you want to do: Unload the SiLabsUSBDriver.text file located in the Extensions directory of the main Library directory.
Be aware that unloading is not the same as removing, it may not prevent the extension from reloading on the next computer startup. Using this unload command successfully should encourage you in your ability to affect the Mac. You can confirm that the extension has been unloaded by performing another "System Information..." check. Let me know what your results are.