System extension cannot be used

I encountered the exact same error, and in trying to find out exactly what this system extension is, this page was the best I could find. However, I didn't encounter the error with Toast (I DO have Toast and I've had it for a very long time, going all the way back to System 9, and obviously have updated it many many times over the past 20 years), I encountered it when installing and setting up ExpressVPN, and based on the name of the file I can't for the life of me imagine why something seeming to do with audio capture would have anything to do with setting up my Mac to run on a VPN. Anyone know what this extension actually DOES? It doesn't seem to be critical to the functioning of ExpressVPN as I've encountered no problems yet, but I've only been running it for 24 hours so far. Any knowledge on this would be greatly appreciated. I've dashed off an email to ExpressVPN's customer support, if I learn anything from them I'll post it here, but I have a strong suspicion that it's honestly unrelated and just some error that it popped up when setting it up. Thanks!

Apparently that .kext is part of a Toast install. Try updating Toast.

The want you to reinstall the extension. Most likely it is a third-party extension installed by software that you installed. However, you've now upgraded the computer and the extension cannot be loaded or the extension has become corrupted. Use the Finder to navigate to the /System/Library/Extensions/ folder. Locate the extension, select the file, CTRL-click or RIGHT-click on the selection, select Move to Trash from the context menu. You will be asked to enter your Admin password. Immediately after putting the extension in the Trash you will need to restart your computer.

From what I can tell that extension is associate with some application you have installed dealing with audio capture.