Can’t find your answer here? Open an issue on GitHub and include your macOS version and TouchGuard version (menu → About TouchGuard).
To hold back a click, TouchGuard has to see that you just released a key and then stop the click from reaching other apps. macOS only lets apps do this with your permission. TouchGuard never reads which keys you press or what you type. It only checks that a key was released.
Download version: System Settings → Privacy & Security → Accessibility, turn on TouchGuard:

Mac App Store version: System Settings → Privacy & Security → Input Monitoring, turn on TouchGuard, and also under Accessibility.
Select TouchGuard in the list, remove it with −, then add it again with + (or reopen TouchGuard). This happens when macOS remembers an older copy of the app.
Some apps turn on macOS Secure Event Input to protect what you type. Password fields, password managers, and terminals with Secure Keyboard Entry switched on all do this. While it’s on, macOS hides typing from every app, TouchGuard included, so TouchGuard can’t tell when you’ve just typed and lets every click through. TouchGuard never turns it on itself.
TouchGuard goes back to “Active” by itself within a couple of seconds once secure input is off.
TouchGuard isn’t seeing your typing. Check, in this order:
Choose a longer delay: menu → Delay → 300 or 500 ms, or Custom….
Choose a shorter delay, such as 100 or 150 ms.
No. It only holds back clicks and taps for a moment after a key release. The pointer still moves, scrolling still works, and clicks work normally the rest of the time.
It holds back clicks from any pointing device during the short window after typing. Most people never notice it with a mouse, since the window is so short.
Menu → Launch at Login.
Press ⌃⌥⌘T, or use Enabled in the menu.
If you installed it with Homebrew, run brew uninstall --cask touchguard (add --zap to also remove its settings). Otherwise, quit TouchGuard, drag it from Applications to the Trash, and remove it from Privacy & Security → Accessibility (and Input Monitoring) if it’s still listed.
Yes, in the download version: /Applications/TouchGuard.app/Contents/Helpers/touchguard -h. See the README.
Yes. It’s free and open source under the MIT licence.