iShowU Audio Capture not showing up

Assuming you're using OS 10.13 or later (High Sierra/Mojave), it's likely you havn't enabled the KEXT.

Apple has become somewhat obsessed with security (probably a good thing at the end of the day), and when installing new drivers you have to confirm that the OS can load them.

This is covered in steps 5/6/7 of Installing iShowU Studio

The important bits:

1. Go to Security & Privacy in System Preferences
2. Make 100% sure the kexts are loaded! (the Allow button only shows if you've recently attempted to load a new kext)

Other Important Things:

1. Waycom Tablet: Make sure you're not trying to click 'Allow' with the pen. it doesn't work. In fact, you can't use any 'assistive' tech at all. You must click with a physical mouse.
2. MagicPrefs: This, from a user recently: 

"I actually just got it figured out early this morning. The issue was that I use MacPrefs for my Magic Mouse 2 to give it more functionality and user friendliness and that “program” had to be disabled for me to be able to allow the kext to be fully installed. Prior to disabling theMacPrefs, I would click allow and nothing would happen. 

None of the above works

Some users have reported not having an Allow button at all.

There doesn't seem to be a particular pattern to this.  My suggestions have been:

• Uninstall the driver
• Reboot (do this! really!)
• Install the driver again.

I've written a much longer article on other things I've tried with various customers. All that I know how have eventually gotten the Allow button to show up. Unfortunately it has been through trial and error.

See: iShowU Audio Capture kext install problems

I want my 'Allow' button back

This is for people that know what they are doing. It requires a bit of work. 'Allowed' extensions are stored in a SQLite DB, which can be modified. Full article here: https://objective-see.com/blog/blog_0x21.html