Before proceeding, please clarify what you’re trying to achieve.
Downloading something from Git and installing it as a Volumio plugin doesn’t make sense in this context.
If you’re aiming to enable kiosk mode on a locally attached screen, the recommended approach is:
Reflash your SD card with a clean Volumio installation.
Install the Touch Display plugin via the Volumio plugin manager.
If you run into issues, feel free to reply in this topic.