1st screen — "This app is not verified by Google"
Click "Advanced" at the bottom left.
2nd screen — An "unsafe" link appears
Click "Go to GSB_FireWall_Agent.gs (unsafe)".
✅ Don't worry! This only means the script hasn't been reviewed by Google — that's normal for custom Apps Scripts. The system only communicates with your own Sheet Firewall spreadsheet, it has no access to any other data.
3rd screen — Select permissions
Check "Select all", then click "Continue" at the bottom.
✅ Activation will start and finish automatically.