If you installed QSS-M outside the App Store, macOS needs a couple of one-time permissions before it will launch and capture raw mouse input.
Open Terminal (Applications › Utilities), then run these commands. Tip: drag QSS-M.app onto the Terminal window to auto-fill its path.
cd path/to/QSS-M.app
Type the path, or drag the app into Terminal to insert it automatically.
sudo chmod +x QSS-M.app
Grants the app permission to run on this system.
sudo xattr -r -d com.apple.quarantine QSS-M.app
Clears the "downloaded from the internet" restriction that blocks launch.
If macOS prompts to allow keystroke/input access for QSS-M, this is needed so the app can read raw mouse input for high-precision movement. If you open the optional launcher with the Option key, you can also click Allow RAW Mouse Input to jump straight to the correct System Settings page. The screenshots below are loaded from the GitHub repo and are not bundled with the app.