Assuming you're using OS 10.13 (High Sierra), 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:
- Go to Security & Privacy in System Preferences
- Make 100% sure the kexts are loaded! (the Allow button only shows if you've recently attempted to load a new kext)
Other Things you Cant Do
- 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.
- 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.
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